Why did he change?

I posted a story on insta and my ex coworker (we both left that job but he left a few months before me) reacted and we started texting because I thought we were becoming friends. He confessed that he used to like me, but when we were working together he just got a girlfriend so I didn’t think much of it. It was all fun and giggles for two days and then I introduced him to one of my friends, and now he takes longer to reply despite earlier saying he was a fast responder and he’s really dry by saying things like “haha sure” when two days ago he would have made a joke. I wanna become friends with him but is it worth it or should I just stop trying?

Why did he change?
Post Opinion