Why didn't my partner come today during sex ?

Ok so we had random sex this after noon he seemed like he was really enjoying it and I thought he had *** as he done what he usually does when he is really enjoying it and is about to *** I was really enjoying it too and I asked him have you *** ? Because I wasn't sure and he had stopped and he said yes then I checked and there was nothing there , I said you didn't *** did u and he said yes I did , but he couldn't of because mo would of seen it and felt it but was nothing , made me feel really sad and I don't know why that happened because the other day we had sex and he *** with in minutes the only difference was we done foreplay first and I dressed up sexy the other day