Seeing that this thread has not been started yet (or I must have missed any threads concerning this topic in the Sex and Relationships forum), I took it upon myself to start it. I'm sure plenty of people have experienced this at some point in their life. Though, of course, some people are predisposed to be able to dust their shoulder and move on easily, there are others who are not so fortunate to have that skill, and a lot of people have self-defeating tendencies wherein they like to cling on to unrequited love instead of forgetting about it and recognizing that it is not necessary for the other person to requite your love, nor is it their obligation to.
Some people are especially attracted to people who they can't get. This behavior is extremely unhealthy, and if you're a person only seeking out unrequited love, it would be better to quit instead of getting stuck in a cyclical trap of chasing after people you can't get.
When faced with unrequited love, the person who is harboring feelings for another person could develop feelings of bitterness and misdirected anger, as a result of not having their affections reciprocated. The person who doesn't requite your love shouldn't be expected to reciprocate your feelings for them. You should also take into consideration that the person is in a very uncomfortable position. If they tried their best to tell you they don't feel the same way without hurting your feelings, then it's probably time for you to stop trying to get them to feel the same way, since if you keep trying, this would be very detrimental to your friendship with the person. As a result, the person could grow to resent you because of your selfish insistence.
You can't get everyone to like you, and if a person doesn't feel the same way, it's fine. For the disillusioned "victim" of one-sided love, this might not seem to be the case and they're "the one" for you. In reality, there will be a couple of people who will be "the one". And what if you do hit it off with the person, and what if they're not as good as you thought they would be? Often the object of affection is wildly exaggerated by the fanciful imagination of the "victim" of unrequited love. The "victim"'s version of the person could be an unrealistic idealized version of what the person really is, and they could be imagined as being perfect. This isn't love, this is infatuation.
In conclusion, unrequited love happens all the time, and if you're stuck in a mindset where you can't "get over" a one-sided relationship, if you're stuck in a mindset where you don't think you can exist without a boyfriend or girlfriend, then you're not ready for a relationship. If you like someone and they don't feel the same way, that's fine, it's not the end of the world. And it's not only one way around, there could also be people who develop a liking for you, but you don't feel the same. That's fine, too. You should not feel pressured to feel the same way. Unrequited love happens, and the best thing you can do about it is to not be hateful towards your love interest. Healthily accept that unrequited love is not proof of your inadequacy as a human being, there are only instances where you're romantically interested with someone, but they don't feel the same way.
If any people also wish to share their experiences with unrequited love, or give more advice, or refute any of my claims. Feel free.