TTC but husband having performance issues

This will be our 6th month TTC and I'm getting really frustrated. Hubby is excited to have a baby and gets disappointed every month when AF arrives, yet actually having sex is getting harder and harder. Got High opk readings yesterday and today, I initiated both days but yesterday things "went soft" and today was a non starter. I never make a big deal of opk readings so as not to put pressure on him but he obviously knows what's going on. I get that it must be difficult for men but I'm finding it more and more challenging to handle my frustration. I'm 36 and he's 40 so it's not like we have all the time in the world!! If another month goes by with half hearted attempts, I'll find it hard to not let it become an issue.