My girlfriend and I have been together for 2 years and I’ve never felt anxiety about sex until just last week. There was a day where we had sex a few times and later that night I wasn’t feeling as horny and I couldn’t really keep an erection, which really upset my girl. The next day I wasn’t too bothered so later on when I tried to initiate sex and she started saying that I’m not attracted to her and she started throwing around all of these doubts and it really hurt:(. Since then she’s apologized and we’ve talked about it, we’ve had sex a few times as well when I was able to be fully present and block out my overthinking. Last night however when I was about to get on top of her I started overthinking about losing my boner and it straight up killed it. Since we’ve had sex I’ve felt better but I still can’t shake off these worries and my anxiety when it comes to sex. I just want to be carefree again 
and this is really making it hard. I don’t want this to negatively affect our relationship please, I need help. I love her so much 
Sounds like it’s coming from her dude, and how she’s treating you. Unrealistic expectations
Think about a time you really enjoyed sex with her. Remember what you did and try to build your confidence up from there.
If she is understanding of your mental hang ups then sex can be a slower, collaborative process. When I openly communicate with my wife that I’m losing my erection, she will flip me over and grind it out until im hard, and she’s wet. We just kiss and enjoy the feeling and it helps me chill out. Is your girl willing to help like that? Is she willing to prioritize helping you get out of your head instead of taking it personally? If not, then the issue is less of a sex issue in my opinion.
Start with having her lay on her stomach and start with a slow and sensual massage. Slow the process down and see if you can get horny during the process. And just see what happens. Now I’m not 100% there but I’ve been able to get an erection and stay harder longer when I slow the process.
break up with her.
Have you communicated with her about how the criticism has affected you? The erection issues need to be an open dialogue, because if you feel that she’s going to criticize you every time you go soft, you’re going to get more stressed about it and go soft more often.
I get it man, am working through the same thing. My lady even started bringing up my ex-wife of 5 years ago, and telling me maybe I should go fuck my ex since I didn’t have trouble getting hard with her. That hurt. But fortunately my erections have now become an open topic of conversation, and I’ve been explaining some of the things I’m learning on Mojo. Now my lady knows if I can’t get hard it’s because I’m anxious about pleasing her and thinking all day about how hot she is makes me stressed at the key moment. Whatever we’ve lost temporarily in the sex area, we’re gaining in the empathy and intimacy area, and I’m happy about that. The hot sex will be back later, no doubt.