He’s interested in more than a fling if he starts doing things that you would normally only do with a girlfriend. He might be skittish about openly admitting it but he still wants it.
I used to go to strip clubs to try to entice strippers into a relationship. Once I realized how stupid that was I stopped. But it goes to show you that people can be incredibly stupid about doing the things they need to do in order to get the things they want. Pay attention to what they’re doing, not to what they’re saying or what context they’re saying it in.