Guys, what would make you want to take things slow when starting to date someone?

I'm currently seeing this guy I met online from a dating app. We met earlier this month and he said he was looking for something serious and wanted to take things slow as in: no sex until we are serious/in a relationship, and enjoying things as they come.

He had relationships before & hooked up with a bunch of other girls but was starting to realize that having sex did not help him with his loneliness. I know this question probably sounds stupid but I wanted to get other people's reasoning on why they would want to take things slow and start dating seriously. Is it better than moving things too fast?

Guys, what would make you want to take things slow when starting to date someone?
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