I think I made a dumb decision🤷🏻‍♀️

So like me and my bf have sex quite a bit and at the start I always let him go in for a little bit without a condom. Is this a risky thing to do like should we put the condom on straight away or is it fine? Also today in particular we’d had sex and afterwards he was hard again so I let him in for a little bit without a condom on. Was this a dumb idea because there could still be semen on his dick or is it fine...?