Yes, this does sound very much like erectile dysfunction and with the help of the doctor and tablets that can be dealt with. However, I wonder if I am reading something else here. You are the one who is worrying that it might be your fault when it is very likely his -- yet he is, perhaps, allowing you to think that you are the one to blame, and that is very man like and very unfair
Your situation requires some lengthy conversation between you and your husband. At 25 he's too young to be fading away at half-time.
Depression is a serious consideration.
Having an affair is a possibility.
Too much porn could also be in the mix.
I don't know his age, but it could be stress or even his testosterone maybe low. Have him go to his doctor
Been nine years since the original post starting this thread. I hope that couple worked it out long ago.