Is (38M) actually like me (25 F) or does he just want to keep things as playful flirting?

I’ve been talking to this guy for a while, and honestly, I don’t know exactly what we are. He flirts with me a lot, calls me pet names and other endearing names, and we talk pretty much every day.

Last night, we spent basically the whole night talking and flirting. We were both doing it, but I’d say he was definitely going harder with the flirting than I was. It felt mutual and natural, and eventually we said goodnight and went to sleep.

Then this morning, he sent me:
“Sorry for flirting with you last night. It was inappropriate at times, I got carried away. But I can’t promise it won’t happen again.”

And now I’m confused about what he actually means.
Is he basically testing the waters and trying to see whether I’m actually into him based on how I respond? Like, he’s giving me an opportunity to say “I liked it, you don’t have to apologize”?

Or does this sound more like he wants to establish that we’re friends who occasionally flirt, but doesn’t actually want it to go anywhere?