The TVTropes Trope Finder is where you can come to ask questions like "Do we have this one?" and "What's the trope about...?" Trying to rediscover a long lost show or other medium but need a little help? Head to Media Finder and try your luck there. Want to propose a new trope? You should be over at You Know, That Thing Where.
Your specific example sounds like Insecure Love Interest.
Basic trope: A character believes he is not good enough for his Love Interest.
Your example: Bob believes he is not good enough for Alice because he did not win the tournament.
It doesn't have to be a romantic pursuit, though.
Another example would be if a character wants to start his own business, but doesn't think his parents will allow him to break away from the family business unless his first start-up is a huge success. It fails to break even in the first month, and he gives up on his dream, even though his parents is actually fine with him starting a new business regardless.
A self-imposed variant of the Impossible Task? Except it's not necessarily impossible, it's just a task.
... That doesn't seem quite like it, but it's a better place to look than Self-Imposed Challenge; that's about "do a thing with restrictions to make it harder", when you're just looking for "do a thing".
Trouble Cube continues to be a general-purpose forum for those who desire such a thing.
Do we have an in-universe version of Self-Imposed Challenge where a character imposes themselves with a task that they must accomplish to gain something else, and is willing to give it up when they fail (or punishes themselves over it)?
e.g. Bob believes that he must win the local sports tournament for the right to pursue Alice. When he fails to do so, he gives up on Alice, even though there is no indication that Alice would only date the tournament champion.
Self-Imposed Challenge itself states I Am Not Left-Handed is the IU version of the former, but it doesn't fit hypothetical example above.
Edited by Adept