Husband has ED

Hello! I’m new to this app- my husband has been experiencing ED (he’s in his mid twenties) and has been tested and confirmed low testosterone... he will be seeing a urologist soon but I’m getting nervous this means infertility. We both want kids soon, and he is the healthiest person I know, weightlifts everyday, low body fat, doesn’t smoke, social drinker, and wants to be able to have sex (he didn’t have any problems two years ago). Has anyone had experience with this/know what the problem could be? And will this be a life long problem without medicine?