my dp is 33 I am 32.
been together for 2 years, always had a brilliant sex life - a normal week at the beginning was 6 times plus. this gradually ebbed to 4 times average which I figured was normal.
He had a vasectomy a year ago and after that would have periods of time where he could not get an erection - either he'd get one but not sustain it, or not get one at all.
in the last month, we've had sex once. many more attempts, where he has not been able to get an erection. Hes really down about it and it's making him depressed. He even said he'd understand if I left him for someone who could have sex 
he went to Dr who couldn't find anything physically wrong. said it was unlikely to be the vasectomy. Hes sending him for blood tests to check hormones and gave him a prescription for viagra which I'm not really happy about him taking.
I think it's likely psychological. I don't know how to help him. I love him, I'd never leave him over this but hes down, he feels like less of a man.
any advice?