Getting it up 🍆🚀⬆️

My hubby and I have been trying for 4 months... He thought it would be easy and literally had NO IDEA about how women ovulate of anything like that...
We had an amazing sex life, doing it 3-4 times a week before we started trying...
First couple of months of trying the excitement took over and we were at it all the time... 
4 months in (and 4 BFN's of course) and today he struggles to get a boner, once he has a hard on he struggles to keep it... He is 28, slim and healthy. 
It's really getting to me, of course I now feel totally unattractive and everything I try I just get greeted with a floppy sausage. 
He says he is stressed and embarrassed by it and assures me it isn't me but it's causing a rift between us ... Especially as we are meant to be trying!! Timing eh?! 
Got me thinking that perhaps it's dawned on him how difficult it is to convince and the pressure has had this negative effect?! 
Anyone had this problem? Any advice how to fix it xx