he's only 27?! shall I give him viagra? 😩

I've been recently seeing this guy who I found out is a virgin. 
He's 27 and we are really into each other however there is a slight problem.
Every time we try to have sex he just can't seem to keep it up. 
I don't mind that he is a virgin as I am also quite inexperienced. I don't know if it's me or what but he always goes limp to the point that we don't even want to try having sex again. Can anyone please help? Should I give him viagra? Would it make any difference?