PE leading to ED

Me and my girlfriend have a good relationship. When we first started having sex, I was able to last for a pretty good amount of time and go multiple rounds. This lasted for about 2 week. Then I came extremely quick twice in a row. Three days later it happened again. Since then, I have not been able to get hard while anything close to sex is happening. I can’t even get hard when we’re making out. She touches me penis and gives me head and Im able to get hard and last a decent amount of time, but when we get anywhere close to sex, it goes away. What can I do? She’s obviously not happy about it and I feel like it’s psychologica, but I do t know how to fix it