Pressure Performance Problems

I've been with my husband for ten years now and we have always had an amazing Sex life. This is our first month TTC and we are both very excited about having a baby. I've been telling him everything I've been researching and learning about the whole process. We already have sex pretty regularly and he has never had any performance issues. I already told him that this week was going to be "sex fest" and he has been excited about it. It started out really well but I've been taking OPKs and as soon as I told him I was ovulating he's had performance issues. Has anyone else had this issue and how can I help him? He is really embarrassed about it and is getting frustrated with himself.