What is my gut telling me???

I've been with my boyfriend for 5 months and we've moved pretty fast since the biggining due to the connection we felt immediately upon speaking. But our relationship did start with lies. He told me he was 24 when I said I was 18 before he even said his age. Later that first week I found out he's 27 and even later that week I found out he's married but separated and because of the green card issue his ex is willling to stay married while she's in another state so he is able to achieve a permanent green card and keep his job.
I stood my ground about how serious this was to me.

He gave me time to think. Later that night he had told me about his abusive parents and my heart went out for him. We grew closer during those days and that first month. But it seems like that honey moon phase left after two weeks. My gut since I lost the honeymoon phase period has been telling me something is off.

We broke up one other time due to miscommunication and repeated arguments started based on him not listening to what I say. We were good the last month but once again those feelings are coming back. He's my first serious relationship it seems incomparison to my high school boyfriends.

He's said he loves me but we don't say it that often. Which concerns me but he also wants to spend every second together and it used to be a fight starter for a while. I can see a long relationship with him in this short time but at the same time I feel we are better friends than lovers. I can only pin point few moments he's vocally been lovey dovey with me rather than his usual actions that show me he cares.

My gut this entire time has been nagging me that i should leave and that there's something I don't know. It's too early for me to even be second guessing what else I could have But I also don't want to be that girl who leaves over fixable things yet my mind doesn't want to fix those things anymore too.

Do I make sense? I mean he didn't even talk about how he felt to me about his family member passing and I feel like his family is completely off the table for discussion. All I wanted was to understand him better but I feel I can't even ask him about his family. Any advice on what I might be going through? Because everything seems great but my gut won't shut up.