<human>: Give me a shortened version of the text

I dated this guy for a couple months. We never made it official although I wasn't allowed to see other people and he said he wasn't (although I found this to not be the case after I ended things with him). Around two months ago, I told him that we should just be friends after I found out that he was flirting with many other girls. We tried to stay friends, but I guess it just didn't work out since we stopped talking and have not talked for about a month and a half to two months. 

During this time period, I started talking to his teammate (they both play college tennis) and we started dating and he asked me to be his girlfriend. At first, I was hesitant because of my history with his teammate, but he assured me that it would be alright since they were not close. I agreed to be his girlfriend although I asked him to keep it quiet since I didn't want to ruin team dynamics or make my ex angry since he has a tendency to get angry and jealous. His teammates know that he has a girlfriend, but they do not know who exactly.

I got a text from him today that said, "Thanks :)". I asked him for what and he said that he thought I would know what he was thanking me for. I replied that I didn't and he hasn't replied since then. The only reason I can think of for him texting me is that he found out and maybe is trying to play some sort of game.

Honestly, I have no idea. 

Any help would be appreciated.

Thanks!
<bot>: Dating an ex's teammate. Ex texted me today saying "Thanks" after not speaking for 1.5-2 months. Is it because he found out about our relationship?