הכרויות נשואים|הכרויות וסקס

I, 27F have been with my boyfriend 26M for on and off 10 years but had been back together 6 months when one night while I was away, a condom went missing. (Yes I counted them) He claimed he’d used it while masturbating out of curiosity of how it feels and/or having a change. He is a sexually experimental person but it never quite added up for me, especially considering the issues we were already having.
Guys, does this sound like it could be legit or does it sound like a crock of shit from your perspective..
All responses are appreciated:)