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When you love someone who doesn't love you back, it hurts. It turns out that “heartbreak” is a very real physical sensation: the pain from rejection activates your parasympathetic nervous system, which is responsible for things like your heart rate and muscle tension. It’s natural to feel hurt if you love someone who doesn’t return the feeling. Accepting that your feelings are normal can help you process them.  Romantic rejection can actually trigger the same response in your brain as withdrawing from drug addiction.  Psychologists estimate that about 98% of us have experienced some form of unrequited love. Knowing you’re not alone may not make the pain go away, but it may be easier to bear knowing that you’re not the only person to go through this.  Rejection can also cause depression. If you notice any of the following, get help from a mental health professional immediately: Changes in your eating or sleeping habits Feelings of hopelessness or helplessness Changes to your normal mood Trouble controlling negative thoughts Thoughts of harming yourself There's nothing wrong with having to grieve, as long as you don't get stuck there. In fact, it's healthier to let yourself be sad than it is to try to suppress those emotions. Denying or minimizing how you feel -- such as saying “It’s no big deal” or “I didn’t love her anyway” -- will actually make it worse in the long run.  If you can, take some time out of your life to process your sadness. This will help create a healing space for you to deal with your grief. For example: when you first realize (or are told) this person will not love you back, then you should take some time to be alone somewhere, even if it's just going for a 15-minute walk at work. Avoid wallowing in despair, however. If you haven't left your house in weeks, you aren't showering, and you're wearing that ratty old sweatshirt that should really just be burnt, you've gone overboard. It's natural to feel sad, but if you don't try to get focused on your life again, you'll just keep thinking about and loving that other person. Your immediate reaction to learning that the other person doesn’t love you in the way you love them may be to think, “I will make them love me!” This type of thinking is very natural, but it’s also incorrect and unhelpful. The only thing you can control in life is your own actions and responses. You can’t persuade, argue, or bully someone into feeling something s/he doesn’t.  It’s also a good idea to remember that you can’t always control your own feelings, either. You can work to control your responses to those feelings, though. Part of creating space for yourself to grieve and to move on is not having this person as part of your life. You don't have to cut this person out of your life completely, but you do need to take a break from him or her.  You don’t have to be unkind or cruel. Just ask the other person to give you a little time to get past the feelings you’re working through. If the person really cares about you, s/he’ll give you what you need, even if it isn’t the most pleasant experience. If the person you're trying to stop loving is someone that you've relied heavily on in the past for emotional support, find a different friend to help fill that role. Ask a friend if you can reach out to him or her when you get the urge to talk to the person you're trying to avoid. De-friend the person on social media, or at least hide his/her posts. Delete the person from your phone so you aren't tempted to re-initiate contact. You don't want to be constantly reminded of the other person and everything s/he’s doing. It will make it harder to keep your distance. Expressing your emotions, rather than bottling them up and waiting for them to explode, can help you accept that you’re going through a painful experience. When we experience loss or disappointment, it’s natural to have trouble dealing with it, at least at first. Don’t belittle yourself for feeling this way or try to ignore the feelings in the hopes they’ll go away. Express them openly and honestly.  Cry if you want to. Crying can actually be therapeutic. It may reduce feelings of anxiety and anger, and can even reduce your body’s feelings of stress. If you want to grab a box of tissues and cry your eyes out, go for it.  Avoid violent actions such as screaming, shouting, punching things, or breaking stuff. While this may “feel good” at first, research suggests that using violence to express your anger -- even towards an inanimate object -- can actually increase your angry feelings. It’s healthier and more helpful to reflect on your feelings and examine why you feel this way.  Expressing your emotions through creative pursuits, like music, art, or a favorite hobby, can be very helpful. However, it’s a good idea to stay away from things that are very sad or angry, such as death metal music. These may actually make you feel worse when you’re feeling down. It doesn't matter how great the person is, if s/he doesn’t love you, you could not be happy with that person. It’s very easy to idealize someone, especially if you have invested a lot of energy in falling in love with him or her. Stepping back to examine the reality -- without being cruel or judgmental -- can help you get some distance from that feeling of unrequited tragic love.  It may also help you to think about the aspects of this person that would have created a difficult relationship between the two of you.  For example: maybe their extreme social anxiety would make it nearly impossible for them to give you the validation you need in a relationship. Studies have even suggested that acknowledging negative things about the other person can help you get past romantic rejection more quickly.  Don’t fall into the trap of saying mean things about the other person to make yourself feel better, though. Ultimately, this type of thinking can make you feel even more bitter and angry, rather than helping you heal. Rejection temporarily lowers your IQ, believe it or not. If you’re having trouble thinking about your feelings in a rational way, accept that it may just take a little time to get yourself back to “normal.” Just as you have no control over falling in love with this person, s/he has no control over not falling in love with you. If you go around blaming him or her for "friend-zoning" you or thinking s/he’s a terrible person for not loving you, you’re being unfair to the other person. This emphasis on bitterness will also hold you back from healing. You can feel upset about the person not loving you without blaming that person. Don’t let your friends play it either. Your friends may try to villainize the other person for not loving you. If this happens, thank them for their support, but say that "it isn't fair to blame him/her for something s/he can't help. Let's focus on me getting over him/her." You can cry over giving up the mementos, but it's an important step in the healing process. Having those mementos around will only make it harder to move on and that's not what you're after!  As you go through each item, think of the memory associated with it, then imagine putting that memory in a balloon. As you get rid of the item, imagine the balloon drifting away never to be seen again. If you have physical objects that are in good shape, consider donating them to a thrift store or donate them to a homeless shelter. Imagine the all the happy new memories that oversized sweatshirt / teddy bear / CD will make for its new owner, and then let these new associations symbolize the transformation you’re undergoing in your own life.

Summary:
Recognize that pain is normal. Allow yourself time to grieve. Recognize that you cannot control the other person. Take some time away from the other person. Express your feelings to yourself. Realize that you are better off. Avoid the blame game. Get rid of mementos.