Why do ex boyfriends come back when they still have better options?

I haven't slept with my ex in 4 years, but I have given him makeout ses until this year
I went no contact after he switched his work schedule. He still contacted me every week to see if maybe I'll answer him. I did a couple of weeks ago, and he's been trying to hang out with me even more so.
He asked if I wanted to do this or that, and I'll just say no.
However, recently, he dropped the facade and wants to "please" me and "have fun" together.
Instead of saying no, I was digging around for answers within our conversation. I found out he's been having more advanced sessions with more experienced partners & they come back to him.
He even admitted he had a partner all throughout
last year, but I assumed last year that he had a lot of talking stages maybe a couple women, but the majority of the time focused on his hobbies because most of the Sundays mornings he was making out with me. For the last 2 weeks, he's been begging from can you come out this day? to yesterday asking if I could come out for an hour.
Also I told him I was eating and he told me to show him, but I said no because I had grease on my face. He said 🙄 You won't even show me that. You're worried about some grease? Why is he circling the block on me when he has better or more recent partners. If he was intimate with the other lady majority of the year, she must be good too
Cuz our relationship only lasted 9 months. Why not hit her line? and why was he making out with me anyway during that year? Also he's coming to work a shift with me today so blocking him isn't the call
Also I don't hate him, he's just not good for me
I don't want to get him in any trouble
Updates
9 mo
Sorry when I mean this year I meant to say January of this year I haven't seen him since then and we only started talking on the phone in the beginning of August He texted me during the no contact months to hangout I never answered.
Why do ex boyfriends come back when they still have better options?
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