The fact that you are asking about it on the interwebs and say that “it’s on your mind a lot” pretty much speaks against your idea that you are not nervous. It might be a good idea to let yourself be aware of the nervousness.
Unfortunate truth is that the more she insists on being “hurt” by something not under your control, instead of enjoying what you have together, the more she is pushing you into performance anxiety and worsening the “problem”. Which I must insist is not a problem at all, until you wish to actually have a baby. Which I assume you don’t, since you are using condoms. (Which you should keep on using, anyway—sometimes people get pregnant without actual ejaculation.)
You say “if I can’t enjoy it”. Don’t you enjoy the sex? Sex is not just about ejaculation. It’s supposed to feel good before it too. If it doesn’t feel good except on the moment of orgasm, that could be an issue indeed.
If you worry about your innervation or whatever, go see an actual doctor. But just to state it again, if you ejaculate while masturbating, it is unlikely to be a physical problem.
And no, you can’t really have caused this by masturbation.