liahgen - I wrote about this a while ago but cannot find the thread so happy to write it again (apologies to those that read it before). Its a bit long but I do suggest a solution which I found by accident at the end which DH might want to think about.
I was very happy to have children and was very happy TTC ... until something happened one day and it spiralled into a nightmare.
What happened was that DW obviously was becoming more anxious (understandable) and we were having sex 'at the right time'. We were doing it every day for a whole week 'at the right time' but it was not working.
I felt gradually under more presure but happy to carry on as it was important. Then one day I was possibly a bit tired and a bit bored and obviously DW knew she was about to ovulate and I just could not perform. DW said it was OK and not to worry but I caught a look in her eye that was like being hit by a truck. I knew she was really upset and disappointed.
When her next period started I just could not get the thought out of my head that if I had not 'failed to perform' she would be pregnant. Next month came and I was worried about not performing again and of course that did not help. The combination of having to do it, the boredom, the lack of emotion, and the worry about not performing made it more and more difficult. In the end I began to dread the next cycle.
I have read the TTC threads sometimes and I have never ever posted there. I just always think that DH/DP must be under incredible pressure with all the ovulation tests that are going on. It is of course terribly important and very emotional thing for women so I never say anything. It is important for men too - but the 'broody' intensity of hoping for conception and counting the days is not there for us blokes.
Your DH sounds like he is perhaps beginning to feel the same way as I did.
Perhaps the best way for a woman to understand how it feels is to imagine your DH/DP marks 10 days on the calender for the next 6 months that you will be required to have sex with him even if you feel tired and not up to it and not only that you must have an intense orgasm. I guess that would probably would make any woman feel really pressured.
As HumpingAntEater said - every time I failed to perform, which was only 10-20% of the time, I just felt feelings of guilt and that got worse every time there was no end result (i.e a pregnancy).
I found the solution by accident. One day, I had 'failed to perform' but then I suddenly realised that having failed then I had absolutely nothing left to lose. I got up and made a cup of tea, had a chat with DW and asked if we could just have a cuddle and be in love not TTC. Taking a break for 30 minutes rather than desperately carrying on and on, I felt a lot better. Then going back to it for fun and love. Well the old magic soon came back second time round. That gave me confidence the next time and of course I realised it did not matter if I failed to perform and realising that fact made it pretty much 100% certain I would perform.
My advice to DH or any man who ever 'fails to perform' is to stop straight away, and then having failed just think to yourself "hey, it does not matter, I have got nothing to lose now". Then go for a cup of tea, take a walk, then come back and just enjoy kissing, cuddling and being in love and it will all work fine second time round.
Doing it at different times of day also breaks the boredom.
As I said - a bit long but hope it helps.