It is very common to hear or talk about "failed relationships." But what exactly does it mean for a relationship to fail? And if you judge a past relationship to be a failure, does that mean that you failed in some way, or that you failed your former partner?
In a certain sense, every relationship that ends—in other words, every relationship except your current one—can be considered a failure. But is survival the only standard of "success" in a relationship? Isn't it possible to think that a previous relationship was a success even though it didn't last? If you and your former partner were happy and you both flourished during the time you spent together, even if only for part of that time, such a relationship can be considered very successful even though it ended.
Perhaps a better way to think of it would be to ask yourself this question: do I regret having the relationship? Am I better off for having had it? Every relationship has its ups and downs, of course, but do you think you're a better person for having had this one? Certainly some relationships can be legitimately written off as "mistakes," but even relationships that were negative on the whole aren't necessarily "complete" failures. As we do with all mistakes, we can and should learn from even the worst relationships—perhaps especially the worst ones!
And as if it weren't hurtful enough to judge a past relationship to have been a failure, it is all too easy to take this failure very personally. You don't just feel that the relationship was a failure, but that you failed, and if you care deeply for the other person, you feel that you failed him or her in particular. Sometimes these feelings of personal failure are general ("I just wasn't good enough"), but other times they can be very specific, such as when you (and perhaps your former partner) can identify specific things that ended the relationship—things that came down to you, rather than to the other person or circumstances beyond your control.
To make matters worse, these feelings of failure may intensify rather than diminish after the relationship ends. For instance, you may be happy when your former partner moves on and finds someone new, someone better for him or her in the ways in which you feel you failed. But at the same time, this may only serve to remind you of your failures, especially if your particular failure is something you can imagine anyone possibly doing better at (such as being a better kisser or listener). In the worst case scenario, this may even make you hesitant to enter a new relationship, if you fear you will inevitably fail the next person in the same ways you failed the last.
But you have to remember that every person has unique needs and desires, and things about you that did not satisfy one person may be welcomed by another. If one person thinks you talked too little (or too much), the next person may love that about you. If one person thought you were not affectionate enough (or too affectionate), the next person may value that about you. It all comes down to being yourself and finding someone who likes you for who you are. To feel that you failed the other person just because you weren't everything he or she wanted you to be is to imply that his or her preferences were more important than who you are. You deserve someone who appreciates the real you, and you shouldn't feel like a failure if your partner wasn't that person.
(Just to be clear, this does not excuse hurtful or inconsiderate behavior, which are clearly failures to show basic respect toward the other person. But a person doesn't fail someone simply by not being the right person for him or her—the relationship may result in failure, but the person hasn't failed personally.)
To look at it another way, failure only makes sense in relation to a standard of success, and only if a standard is reasonable should failure to meet it carry any weight. If I fail to become an Olympic athlete or a Supreme Court justice, I shouldn't be very disappointed, since these aren't reasonable standards of success for me. Being a good romantic partner is more reasonable for most people, of course, but only given a good match—that is, only if the other person in the relationship has needs or desires that you can reasonably expect to meet. If not, then failure is too harsh a judgment to make of oneself.
For example, if you make an average income and your partner expects to live in a mansion, you haven't failed because you can't provide this for him or her. If your partner wants lots of affection and you're not the kind of person to provide it easily, then you haven't failed him or her—you're just not right for each other. These relationship may fail, but if the two of you are that incompatible, it was going to fail anyway—but not because of you. And since you have not failed personally, there is no reason to expect that you will fail someone else.
So don't take failed relationships to heart—learn from them, certainly, but don't beat yourself up over it or write yourself off as a failure. The same things that disappointed one person will thrill another, and the only way you'll fail is by not trying again.