Let's Be Adults

I have not been in a serious relationship since 2009 and even back then it wasn't serious. So Coach has been the only guy that I've dated (had sex with) since then. (Not counting meeting Robert). Well, when I "gave in" the other day, I became concerned. I mean, he's the only guy that I've been intimate with, but I'm sure I'm not the only girl that he's been intimate with. Especially since I've seen another woman at his house. So, I was a little bothered when he wouldn't answer my question. I simply asked, "When was the last time you had sex with someone other than me?" He didn't respond. Maybe it was because I text him...but I thought it was an important questions. I mean, we didn't use any protection. So, I want to make sure that we are being safe and responsible. So, why didn't he respond? What it the way I asked or how I asked? If I can allow him to see me naked, why can't I be adult enough to have a mature conversation about sex? I sent him the text on yesterday around 7pm....Let's see how long it takes for him to communicate with me....Hmmmmmm.