Failed relationships are not always such a bad thing. The silver lining in this tragedy is that there is a reason or several reasons why a relationship between two persons did not work out. And you should be grateful for those things. They can show you what you want from someone, what you need to maintain a relationship, how to do better next time, what you need to improve and change, and what is important to look for in someone you want be with. Memories and mementos are not the only things you can get from your past romance. You now understand more about yourself, your partner, and relationship especially the one that just ended. It becomes evident that you need to be with someone who wants the same things as you, you might realize that serious, committed relationship is just not for you at this point of your life, or you know that it does not matter how gorgeous someone is if you cannot trust them or they you. You can see that love, passion, and romance mean nothing and last shortly as long as they are not supported by the likes of maturity, patience, and honesty. It goes without saying that there are tens of different things that you might discover from destruction of your own relationship. But let it be something that can help you be a wiser man or woman and point you in the right direction.
It may not be apparent at first, but if you spend time to chew it over you will be able to see it. And you kind of have to do this so you will not commit the same mistake again, whether it is with the same person or with an unknown subject. As long as you do not do something about what caused your relationship to fall apart last time, then your next one or ones will not be much different. Whether or not it is the same way as before, it will end. Sometimes you can figure out the reason yourself and the other times your ex or friend will enlighten you. Whatever it is they told you or you thought of, you need to evaluate it first before you decide the validity of it. Try to be objective and admit, at the very least to yourself, if something was indeed your fault.
Hindsight is always 20/20. Now that you know better, you cannot stop thinking how you should have tried harder, you should have given more, you should have listened to them, you should have seen or known what you needed to do, and you should have thought about the ramifications. Nevertheless, merely realizing your error is not enough for you need to investigate the reason behind it so you can prevent yourself from ever doing that again. Ask yourself why you did something the way you did it and the answer will always be similar every time. You believed that it was what you wanted, you thought you were right, and at the time it was the easier thing to do. The lesson here is that there is always a chance that you could be wrong about something. Let this show you the importance and value of always thinking carefully and at length at least once before doing or saying something harmful. What you can learn from this is that most of the time, the hard choice is the right and necessary thing to do.