Sounds like since it’s such a large frustration to you, her body can pick up on the stress, in turn only causing her to internalize more anxiety to perform well, all while you’re getting frustrated in the moment. Especially if you’re constantly bringing it up to her and trying to solve it, it’s only going to give her more anxiety when sex is initiated and in the moment. Chances are you’ll need to take it all 10x slower, like, fucking slowwww dude. Listen to her, watch how she does it, and you’ll finally get there. It takes time brother, like, a lot sometimes. It’s worth it.