he regretted ?

so I had sex with a co worker so was my friend.. and today we was outside talking on our breaks and he was talking about how certain girls fell under the list of girls he regretted fucking. as in he was drunk/high. mind you both times we did it one time drunk and the other high WELL he said a few names and I said well do I fall under that category and he said 50/50?? LIKE WHAT DOES THAT MEAN? I asked and he said he doesn’t know and I said well sorry you regret fucking me but you should be THANKFUL! and he pulled the he was fucked up card but he wasn’t the first time. the 2nd maybe but he is the one who invited me over. SO my question is WHAT DOES THAT MEAN. how can you half way regret sleeping with someone?