Last night my boyfriend and I had sex for a while, but he got soft without cumming. So we talked for a while and then I left the bed for a few minutes to turn off the lights, brush my teeth etc. I know the condom was still on when I left the bed. Then when I came back he wanted more sex. I checked with my hand and noticed he didn't have the condom, so I said "Aren't you forgetting something?". He said "Oh, it must have slipped off. It's so thin, so it's hard to feel." He/we didn't make any kind of effort to find the lost condom on the bed, we just took out a fresh one and proceeded with business.
This morning I found the condom on the floor where it wouldn't end up by just falling out of bed. So he must have put it there, but giving him the benefit of the doubt I guess he could have noticed it in the bed later and just dropped it on the floor...
So I guess my question is: Is it possible for the condom to slip off like this without him noticing it happening, and not noticing it's missing when becoming hard again? Or was he trying to trick me into having unprotected sex?
Some more background info: We have recently gotten tested for STDs and he was talking of having unprotected sex after the test, but before we had all the results.