Hot and cold after 2 dates?

I started dating this guy a few weeks ago. We were texting for about a week before we met up in person.
Both dates were amazing, even he said so after our first date that it was the best date he’d ever been on.
In the beginning he would initiate conversation all the time, he would be the one texting me all day long sending me links to love songs and telling me how amazing I am and how lucky he feels to have met me. It went from 0 to 100 real quick but it felt kinda natural.
On our first date he actually said to me that any guy who f***s me over is an idiot and that I’m a catch.
Everything seemed so amazing!
Until shortly after our second date, which was still great and nothing seemed different on the night.
After that he started to withdraw suddenly.
His attitude changed from texting me twice if I hadn’t replied in a while to not replying to my messages at all.
I questioned him and it was always an excuse. ‘My phone died’ ‘I didn’t have my phone on me’ ‘I was doing this and that’. I tried to be cool about it.
Except it just felt so strange, he didn’t call me babe or beautiful or any cute nicknames anymore, he stopped acting as if I was this amazing person he felt lucky to be with, and just felt really detached.
I found out he’s been dating other people, which is fine because he’s single but he specifically told me he wasn’t when I hadn’t even asked. So i just started questioning other things he’d said like maybe he wasn’t always being as honest as I would have liked him to be.
We had an argument where he said he wasn’t looking for anything serious and he felt as though I was coming across as if I was trying to pursue something. Wtf? He pursued me! He was the one texting me first every day, asking me out all the time, telling me he was going to treat me right.. Not the other way around?
So I was polite to him and just said I understood and respected it but that I felt as though some of the things he’s said and done were a bit misleading.
He said he still wanted to hang out with me. I agreed. But in the back of my mind I kind of made the silent decision to move on and open myself up to anyone else who might come along because I didn’t see the point in counting on things to work out.
Since then, he’s texted me here and there. My replies are now about as slow as his because I guess I don’t see talking to him as a priority anymore.
I couldn’t figure out if maybe he was just not interested anymore and didn’t want to hurt my feelings, so I asked him the other day if he wanted to hang out.
He assumed I meant that day and said he was busy (I had work so I couldn’t have anyways). I said that I meant soon when he was free and he replied saying he’d be happy to. So I said to just let me know when.
He didn’t reply at all. This was 3 days ago and he just now messages me asking me how my weekend was.
I am literally so confused as to where this kids head is at.
Why would he consciously make an effort to talk to me if he’s no longer interested? Or why act as if he’s not interested if he still is?
My only 2 theories are that he either really isn’t interested in anything serious with me, and he’s just keeping in touch enough to continue getting whatever he’s getting out of this situation (and he’s not getting much so it doesn’t make much sense, if roles were reversed I wouldn’t be making an effort).. Or he’s backed off because he felt as though he’d gotten me and the chase was over. Now I’m not really putting in any effort, im not where he wants me anymore. I’m not as easily available or needy. My life’s continued on with or without his attention.
Or I could be totally wrong my both my theories might be way off. So that’s why I’m here.
Any advice on what might be going on here and how to deal?