What’s Happening Here

I have been dating someone for 4 months now. I think things were going great at the beginning and still are but I do feel a shift. I admit I am an overthinker; I’m getting help for that. On Saturday, we had an excellent time, stayed over together too. It was all really good. Sunday he’s getting text messages at 8am, shady about it and said he had a lot to do and left. He left with a “take care, don’t be a stranger, ttyl, I’ll text or you text. Bye.” Super weird. He’d already been hinting his Sunday would be off limits. Left and never came home until 11 that night with no explanation. I do want to ask if he’s seeing other people and I do want to tell him that I do want to be a priority. I do not think I can do dating and we’re seeing other people on the side. I’d like to know any thoughts. It’s very hard to describe other events and details because this is an app I’m not familiar with and I can’t cram a whole 4 months here. This post is very brief and I’ve left out some detail.