Advice - how to go from casual to serious?

Context:

In Jan2024 went on a few dates with a guy and I ended it bc he flaked on me but in actual fact he was telling the truth he had a migraine.
Then a month later we Bumped into each other on a night out and we slept with each other.
He was messaging me for a few days and making convo but I said to him that his messages are really dead and he said the reason was because he was moving to Amsterdam.
He moves but every time he was back in England he would ask to meet up to sleep with me but I’d be busy.

He came back in December and asked to meet up with me and I said that I’d let him know and I was seeing someone at the time. That ended and I messaged him to meet and when we slept with each other he asked me if I’m still seeing that guy and I said no and he said ok good because I don’t want to be a dickhead.

We don’t speak for a month and it’s Jan - he messages that he has fully moved back to the U. K. now. He says he’s going on holiday and he’ll message when he’s back to arrange a date to meet. I message him that I’m not interested in sleeping around and he says no worries that’s all good !

We don’t see each other but I message him saying I take it back andwe meet up a few days ago and I came to his.

We spoke and he said when we dated he wasn’t too sure if I was into him bc I was standoffish and when we met up in December he said that I was not that interested.

He also told me how he didn’t fully know if he was going to Amsterdam or not either and only found out 2 weeks before going.

This time we spoke a lot and got along with each other quite a bit and we both opened up and he said to me that I seem more comfortable and easy to talk to. He was also very affectionate and cuddling me loads.

He asked me how I knew this guy that I follow on IG and i said through hinge. He asked if he was the guy I had dated and I said no and he’s goes ok that’s good just checking. They aren’t friends and went to the same uni. The last time they spoke was 7 years ago.

Advice - how to go from casual to serious?
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