Guys why do you act hot and cold towards a girl?

Why do guys act hot and cold? what is the reason for it?
Are they do it intentionally?

There's guy acting hot and cold for the past while one moment he's very hot then can go cold quickly in his behaviour.
we've met up a few times and he keeps acting hot like he wants to meet then it doesn't happen but he'll keep agreeing to it. Seeming up to it. The last couple of times he lost his hard on so I'm not sure if he's just fearing if the sex in case it happens again? if it goes badly but seems like he still wants to meet just goes extremely hot up for it then cold. We have spoke about non sexual stuff too.

I've ignored it for the passed haven't mentioned it. Should I bring it up saying something like.
"I haven’t heard from you in a while. I miss you. Did I say or do something wrong?”
to see what he says? or would it look clingy?

Updates
+1 y
Or does he need space?
Updates
+1 y
Will I text him in a few days?
Guys why do you act hot and cold towards a girl?
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