Extremely confused!

So my finace and I are going on 2 years together. Last summer we had a little break up in which a few weeks prior to it I already felt him different and bottom line is there was a girl involved that he just completely disappeared off and then we worked things out. He just recently moved in with me and lately like litterally in the last like 3 days I started getting that weird vibe from him again. It may sound stupid but even when we are sleeping I feel the difference. 
So out of thin air this childhood friend adds him on Instagram and she liked one picture of mine and unliked it very quickly that I barely could of caught that if I hadn't already been on Instagram. I asked him who she was and he said a childhood friend practically her father is like an uncle to him. So yesterday I had posted a nice post about letting God do things for me. He asked me what was up with and actually mentioned that he thought it was because he added his friend. I honestly hadn't thought about her since I asked him who she was. So I asked him should I be worried and he said no that they only ended up texting about him painting her dads house. So he decided to stay in his dad's house yesterday since it was his dad's birthday. When he dropped me off his phone rang and his eyes completely came out of his head but then it was just his mom. I actually spoke to him about it and he decided to just throw out there that he's been thinking a lot about marriage and he doesn't know if he wants it. Marriage has always been his idea by the way! Don't get me wrong I want to have a nice wedding but I never just decided to do a guest list on my own or contact venues. 
Call it woman's intuition but I had to see for my self. I checked his T-Mobile account and there it was. They texted all day yesterday and spoke on the phone for an equivalent of about 4 hours all day! 
I DONT KNOW WHAT TO DO!!!!!