He’s been completely ok with the no-sex-before-marriage thing and never pressures me in the slightest. In fact I’m pretty sure he wouldn’t, even if I had a moment of weakness and gave him the go-ahead. When it comes to marriage I told him I want to get married in the Church (he’s baptized Catholic), our children MUST be raised Catholic, and we need to use NFP. When I mentioned NFP, he said he’d be fine with it as long as I can show him studies about it’s effectiveness, I did, he read them and agreed.
Last night we were talking and he admitted that NFP is starting to scare him because he would really like to avoid children for at least a couple of years after we get married (we’re both obsessed with travelling the world). I promised him I’d send him more research and he said it’s that, as well as the fact that without a physical barrier (i.e. condoms) he would feel really really nervous not knowing if it “failed” (apparently he never let his previous gf use just the pill either).
I could see how sincerely saddened and scared he was - this wasn’t him attacking my beliefs by any means, and it broke my heart. I know I’m following my beliefs with all the “rules” I’ve set up and I don’t regret it, but I can’t help but feel awful for all the concessions he is making for me.

He has been SO open and ok with everything and I know he wants to be ok with NFP but just isn’t right now.
Has anyone dealt with an atheist husband + NFP? Other than showing him more studies and getting him to chart with me when the time comes, how can I help him feel better about it?