What is he thinking?

Im 24, he’s 29. Neither of us have kids and we live separately.
I started dating my current boyfriend 5 months ago (In the middle of a lockdown, so we’ve never been able to go on a proper date).
He works 9-5 Monday to Friday, and I work 6 days on, 4 days off (60hrs p/w) - So to me, time together is valuable.
Lately, he has been saying we see each other too much (he goes to his best friends house 3-4 nights p/w, when i’m at work or on occasion when i’m off work).
Obviously when I’m off work, and he chooses to go out rather than see me this pisses me off, I raise it with him and he says there’s nothing wrong just that he needs space?
In the beginning of the relationship I found out he was messaging girls behind my back, and since then I’ve seen other things that have annoyed me. So that, added with how he acts sometimes makes me doubt things.
When we’re together it’s amazing, we don’t stop laughing, he posts me on social media etc, he’s mentioned starting a family with me...
However, it just doesn’t sit right that he’s happy seeing me 2/3 times a week?
Like we’re both adults, I said that to him.
He says he doesn’t have any reason to be at home all the time (he means a baby), so he can go out when he likes.
His friend that he sees is single and also has no commitments.
Am I just over thinking and worrying? Anytime I say there’s an issue I get gas lighted or he says I’m guilt tripping him.
I really want us to work, there’s only issues when we aren’t together but am I the problem?
What is he thinking?
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