need advise

so i have been with my partner for a year and a half things were great I felt happier than I'd ever felt, I have 2 kids that he took on and is a great step dad and was/is an amazing boyfriend so last Sunday we had an argument and almost split up he spent the day at his dad's because we don't argue in front of the kids. I spent most of the day cleaning and just living normal life with the kids whilst j thought about a lot different things including what life would be like if we wasn't together and I didn't get upset like I thought I would. the last week has been so different I don't know if it me or him but we are not as close and we haven't had sex which he used to not be able to keep his hands off me, I think maybe I'm over thinking things but I just don't feel the same, I don't want to say anything until I know for sure how I'm feeling. has anyone been through this and can give me advise? p.s it wasn't really an argument just he wasn't talking to me about how he was feeling and was not being himself