Infertility? 💔

My s/o and I are def not ready for a baby but he has some concerns. I have 2 daughters, 6 & 8 (from my ex husband) and according to my OB, I am EXTREMELY fertile. Both of my daughters were conceived while on birth control (the pill, and yes I used it correctly). My s/o has no kids and he says he's tried in the past to have kids with no luck. He knows its him because his exes all have kids now and He just found out his most recent ex is pregnant. He got a little upset finding this out because that just proved to him that he's the one with fertility issues. He's never gotten tested for it and he's really sad right now because he really wants kids. He's an amazing father figure to my daughters but I know he wants one of his own. We've talked about it but not ready to try for one just yet (because if it happens, we're not ready, we don't live together, and I want to complete my nursing degree before I get pregnant). My question is, has anyone/anyones s/o been through this? What are some things you did? Treatments? Diet? What worked and what didn't work? Were you able to conceive? I keep telling him theres a lot of treatments he can do but obviously he feels what he feels and I cant take that feeling of sadness or defeat away until (if and when) we get pregnant. I'm 29, he's 30, so the clock is ticking. But it breaks my heart to see him defeated by it.