Some people, including myself, get upset if their key (the way they are) does not fit in a particular lock: their romantic advances are spurned by the person of their desire.
Locks and keys are “made for each other”, and there are only certain locks which will fit with certain keys. No matter how attractive a particular lock may seem to you, if it does not work with your key, further fumbling will not make it work. (You can try hairpins, but that is a different matter – and they’re not very convenient to use, and will not work with all kinds of locks).
So, eventually you figure out that your key will not open up a particular lock you were interested in. You can still be friends with that lock, and hopefully be understanding if another key comes along, which will be a good fit for that particular lock. Maybe there’s some childhood trauma which needs to resonate in a particular way for that particular person. Maybe your mustache reminds them of a past lover who was abusive. Maybe this, maybe that.
Why do you need to know the reason that your key doesn’t fit? Only to still feel worthy.
But you are. Every key is worthy, as it unlocks it’s own lock.
Go and find yours 🙂