I think I ve killed our sexual relationship?

My girlfriend and I have bee together for 3 years. In the beginning sex was not a problem, we flirted, I was always wet and stayed that way during sex. It wasn t so awkward. Now for some reason I forgot how to be desirable, I forgot how to seduce and make her want it. I don t know what s wrong with me, it used to not be a problem, now I can hardly get wet, I m only 30. At first I thought it it was her not wanting to have sex anymore but now I realize why. It s me, I don t turn her on, she s still attracted to me and wants me but I don t make her want it. I m just like let s have sex and it s become... That. I don t know wtf happened to me. Now when we are ready to have sex she just lays there on her phone and I m being super awkward, she s like make me put my phone down then, make me want it. And I have no ****** clue what to do. Its embarrassing, and confusing for me. I really want it I love her and very attracted but somehow my mind and body get in the way. Now tonight, the same thing happened and we just ended up arguing. From the look on her face, I know she s done. What do I do?