I've been dating my girlfriend for around 2 years now. I love her to death, I love seeing her every day, she is the love of my life. However, lately, I have been really struggling to stay hard whenever we have sex (Side note: I'm not on HRT yet, so this isn't a transitioning issue). This didn't happen the first several times we had sex (she's the only person I've ever slept with and is also transfem), but for some reason, I either go flaccid while inside her and slip out, or it takes so long for us to get things we need to get started that my penis goes soft and bends when she tries to put it in. It's gotten to the point where she doesn't want to have sex with me anymore I genuinely don't know what the issue is. I'm very attracted to her, so that can't be it. I don't know if it could be that I only ever masturbated to porn before her and never lasted very long doing that or if it's performance anxiety since she's a lot more experienced and kinky than me. I'd like to get to the bottom of this because it seems to be putting a bit of a strain on our relationship. We both love each other dearly, but I just haven't been able to keep it up to satisfy her. I really crave intimacy in a relationship. I don't necessarily need sex, but I'm worried she won't even want me to touch her anymore. I'm worried that she might suggest me finding another partner to do sexual stuff with (she's polyamorous and has encouraged me to explore being poly before) but I feel like it wouldn't be the same since I love her so much.
Sorry for the long-windedness, but basically what I wanna know what my issue could be and how can I fix this? Thanks in advance for any advice