I totally get what you're saying. I mean, when I was dating I once had a woman plan out our impending marriage 20 minutes into our first date. That's way too bought in!
But with my wife, the first time I kissed her, her response was "more." And then we spent the next two weeks together basically non-stop. I guess that's what I mean.
I had a few guys get ridiculously possessive on dates 1 or 2. Calling me their girlfriend without that ever having been discussed, etc. For me, that's way too bought in and my cue to exit, stage left. I'd call the mental ward for someone talking marriage on date 1 or 2.
First date with DH, though, I admit he started to kiss me and I forgot where we were for a few hours. Thankfully, it was a goth/techno club where couples making out was extremely common. It wasn't until I started unbuttoning his shirt that I came to my senses. He didn't put out
til our 3rd date because he was playing hard to get in hopes I'd keep him. Three weeks later, after spending a LOT of time together in person and on the phone, we were..uhh...well, sort of arguing on our way to that same club. Voices were being raised and passions were high. He said, at the end of a point he was loudly making, "Don't you know how much I love you?" And I yelled back "Yeah, well, I love you, too."
Before that, I'd have said that was waaaay too bought in at 3 weeks. Yet, there we were and here we are 20 years later.