Why are my erections failing? A few times now, my girlfriend and I will be going through foreplay and I ll have an erection, but after a couple minutes, the erection goes away. This is extremely frustrating and rather embarrassing when we re trying to have sex. I ve noticed that I m much more likely to lose my erection if it s hot (temperature wise) in the room. Also- possibly unrelated- we ve found that my penis almost never fits if she is on top during sex, but any time that I am on top, there s no issue. Please help me out with these two problems. Thank you!