Think about what you know about your ex. Tuning in to your knowledge of yourself, your ex, and your relationship is the best possible way to know how to interpret observed behavior. Think back about your relationship and how your ex communicates and deals with conflict. Are they blunt and straightforward? Then they're probably not hiding their feelings and you'll be able to tell if they miss you. Did they used to avoid you when they were mad and upset? Then their silence now probably means they're not pining for you — they're probably upset and angry and don't want to talk. Are they someone who lingers on things and dwells on the past? Then maybe they are thinking a lot about you. Use what you know about your ex and their personality to interpret their behavior toward you.
Keep in mind that behavioral interpretations are filtered through the observers biases and wishes (when it's a personal relationship), and thus you tend to see things that are not actually there. If your ex is big on texting and you haven't heard a word from them since your breakup, don't try to interpret that silence to mean they miss you — they'd probably be texting you if they missed you. Try to look at their behavior from a more objective perspective.
Note how often they contact you. If your ex doesn’t miss you, they probably only contact you if they really have to (for example, to arrange picking up their things from your house). If they do miss you, they will probably have a hard time resisting the urge to pop up in your life from time to time.
When your ex gets in touch with you, they may not have a specific reason. They might say something like, “Hey! I was just wondering how you’re doing.”
An exception to this might be if your ex was the one that ended the relationship, but also expressed a desire to remain friends. If this is the case, getting in touch with you could be a sign that they miss you, but they may also simply be trying to stay friends.
If your ex is constantly “drunk dialing” you, which means that they contact you in the middle of the night after they've had a few drinks (and thus, is less inhibited) there is a pretty good chance that they have some feelings that they haven't been able to work through.
Think about how they behave when they contact you. If they're contacting you, they probably are looking for excuses for calling so that they aren't continually contacting you for no reason. They might ask for advice or for help dealing with a problem. They might also try to steer the conversation towards deeper topics. For example, they might talk about things they want to accomplish in their life or thoughts they've been having about the kind of life they want to live.
When they contact you, do they “accidentally” call you by a pet name that they used when you were together? This slip of the tongue could indicate that they still think of you in that way.
Note how long they take to get back to you. When, and if, you contact your ex, how quickly do they respond to your text or email? How long does it take to call you back? Although one instance of taking hours to respond doesn’t necessarily mean anything, if they consistently ignore you for hours or even days, they probably aren't missing you that much.
If an ex is completely ignoring your calls and messages, avoid sending more messages or calling again. If you’re missing them, this can be very hard to do; however, imposing a rule on yourself that you won’t get in touch with them will help you move on.
Observe their body language. If you do end up in the same place as your ex, notice their body language around you. If your ex is avoiding eye contact, they have their arms or legs crossed, and isn’t smiling, they probably aren't very happy to be around you.
Although body language is a great indicator of how a person is feeling in that moment, it won’t tell you everything. For example, your ex may miss you terribly, but they may act like they want to have nothing do with you in your presence. This may be because they're afraid of being hurt again.
Try to observe their body language and combine it with the other information you have. For example, if your ex’s body language is suggesting that they don't want to be around you, but they're calling you every day, then it may be that they do miss you, but they're feeling defensive in your presence.
Notice if they show up in places you frequent. If your ex randomly drops by your work, or shows up at a place that they know you frequent, it probably wasn’t an accident. If you have mutual friends, they might find out where you will be and “coincidentally” be there too.
If your ex does show up somewhere that you are, don’t forget to observe her body language. Do they keep glancing in your direction? If so, they're probably trying to observe your behavior, too.
Browse their social media. If you are still friends on social media, observe their postings and interactions carefully. Are they posting lots of vague and/or sad posts (sad songs about lost love, etc.)? Are they commenting on old pictures of the two of you or “liking” them? If so, it may be a sign that they're having a hard time dealing with the break up.
Remember though that social media is not always an accurate depiction of what’s going on in someone’s life. Even someone who posts lots of pictures looking like they have the perfect life could be dealing with major emotional issues.
Don’t go overboard with browsing social media. Respect the privacy of your ex, and limit yourself to checking once each day, at the most.
Pay attention to how often they interact with you on social media, as well. If they tend to like your posts, for instance, it means they're still keeping tabs on your life—so they may still have feelings for you.
Notice how they act around you in social situations. If you and your ex still hang out in a group of mutual friends, carefully (but discreetly) observe how they behave when you are in a group of friends together. If your ex seems agitated when hanging out with you in a group, and tries to avoid interacting with you, it might be because they are still dealing with lingering feelings.
Be careful though. Your ex may still be dealing with old feelings, but that doesn’t necessarily mean they're missing you. For example, they may be very angry at you because you really hurt them with your actions. Try to keep your judgments about their behavior within the context of your breakup and past interactions.
Take note if your ex constantly glances at you even when interacting with other people. This could mean that they're interested in observing your behavior to see how you’re feeling, too.
Talk to mutual friends. If you have mutual friends that you trust to keep quiet about your investigating, ask them if your ex has mentioned anything about you. Your mutual friends will probably be able to give you great insight into how your ex is doing.
If you have mutual friends, but are afraid they’ll tell your ex you asked about them, you can try asking very casually. For example, instead of being really direct, you could say something like, “I was just wondering how (name of your ex) is doing? I know they had a big exam coming up, and I hope it went well.” They may still catch on, but it won’t be as obvious as saying, “Has (name of your ex) said anything about me?”
Avoid constantly hassling your mutual friends about the topic, though. It’s OK to bring it up once or twice, but if you bring it up all the time, they will probably get annoyed.
If your mutual friends say something like, “I’m sorry, but I really don’t want to get involved in the situation” then respect their wishes. This doesn’t mean they don’t care about you; it means that they care about both and don’t want to get dragged into a “he-said-she-said” scenario or choose sides.
Decide whether or not this is a good idea. The easiest and most direct way to find out whether or not your ex misses you is to ask them. Unfortunately, for most people, this is also the most intimidating way; however, simply talking with them is likely the quickest way to figuring out what's going on.
Be aware that, depending on the person, some people may not be honest about their feelings, especially if they are afraid that you are trying to hurt them.
If you and your ex aren’t able to communicate without getting into a big fight, meeting up to try and have conversation about a topic like this may not be the best idea.
Asking your ex outright seems scary, but it can save you a lot of confusion in the long-term — instead of spending time trying to interpret their silence or what, exactly, their use of that smiley emoji meant, you'll know flat-out if they want to get back together. If they don't, then you can begin the work of letting go and moving on and not waste your time on someone who no longer wants to date you.
Get in touch with them. You can contact them via text or email, but the fastest way is probably just to call her. Keep your conversation as light and friendly as possible. Ask them if they’d like to meet up for lunch or coffee because you want to talk about something with them.
Understand that they might refuse. If they don't refuse to see you it’s a good sign that they don't miss you, or if they do, they aren't ready to see you yet. Try not to get angry. Instead, be respectful of their wishes.
Keep it light. If this is the first time you are seeing each other since the break up, the situation will probably feel a bit awkward. Take the initiative and try to keep the situation as light as possible. Ask them how things are going for them (e.g. with school or work), and let them know a few things that are going on in your life.
Try to keep the conversation on light things and don’t just jump straight into talking about your relationship. This will help lighten the mood, and let them know that you aren’t trying to start a fight.
Wait for the right moment. If you are at a restaurant or cafe, and are ordering food and/or drinks, it might be a good idea to wait until you have gotten your order to bring up the reason you wanted to meet. This will ensure that you aren’t interrupted continually by the staff wanting to take your order, bring you your food, etc.
If you are ordering drinks, avoid alcoholic beverages (if it is relevant for you). Though you might think having a few drinks would help you relax it may also lead you to saying things you didn’t want to say or you might get emotional.
Be honest. Although it might be scary, at some point, you will need to bring up the reason for meeting. Start by saying that you appreciate them meeting with you, and that you’d like to talk about some things that have been on your mind. If you still have feelings for them, then be honest about it.
If you miss them, telling them the truth about your feelings may make you more vulnerable, but it may also mean they're more likely to open up about their feelings for you.
For example, you could say, “The truth is, I’ve been thinking about you a lot. I know we broke up, and I respect your feelings, but I’d like to find out how you’re feeling about me.”
You could potentially do this over the phone or over text, but having a conversation in person will allow you to observe their body language and facial expressions.
Decide what to do next. If it turns out your ex misses you, and you miss them too, then it’s time to decide what to do about those feelings. Try to have an objective conversation about the reasons you broke up, and whether or not it’s worth giving it another try.
If it turns out they don't miss you, then you know you can move on with your life. Don’t try to make your ex feel things that they don't feel.
Although it is very difficult, try to think rationally about whether giving it a second try is a good idea. You may discover you both miss each other, but getting back together still isn't a good idea. For example, if you fought constantly about basic values (e.g. religion or ideas about how you should live your life) giving it another go probably won’t end any differently.