Why is my ex acting like this?

My ex,a friend and I went out to the a bar on april fools day.My ex was rubbing my back,danced with me and saying that i was cute,y lady,darling and sweetie to me and my ex has a girlfriend.He has been texing me everyday except for 3 days. Monday comes and he is asking if i wanted to watch a movie with him and a friend and i decline and hes like ok.An hour later he asks me if i have killed my roommates yet and i explain to him the drama. Hes texts me to go there for harry potter and says its fun.I didn't go to the movie.A couple days later he is saying hes fighting with his g/f,he is stuck and doesn't know what to do with her and asking if he has habits or mannerisms that make him unlikeable to which i say no.Later on he says how she is being a ***** because at least once a day she gets mad at him for something stupid then turns around on it in a second.She's always so hot cold and now that he called her on it she's extra pive aggressive.The next day he is saying how he has to deal with his g/f and cant decided whether or not he should break up with her. And over the weekend i went into the ditch and he freaked out about it asking if i was ok and again and if i fell asleep or if i was hurt and he was glad that I was safe.