No sex... should I be concerned?

My husband and I have a fantastic relationship. We have everything we want, we are happy, we adore each other, it's been amazing these past 5 years of marriage. The ONLY fault in our relationship is the lack of sex. We haven't had sex in 5 months. It's a touchy subject as he states that he has performance anxiety and gets so scared of losing his erection that he can't even get it up. We have explored a few things in bed but each fun and new idea only lasts 3 or 4 sex session then he gets the anxiety again and we go through a dry spell. He has been tested and his testosterone was on the low end but not low enough for medication. Now, I don't "need" sex to be happy. I have been so happy with him that the lack of sex doesn't bother me much... but it concerns me. It makes me feel insecure. I fear that when he goes out with his guy friends he will get drunk and make poor decision due temptations and a lack of satisfaction from me. Should I be worried?