Assuming you start dating at the age of four, with an average turn over of 10 days, over the course of 25 years you could date eight hundred and ninety people.
Now, there's a similar number you might be more familiar with. It's the number of class mates you've had in school. Let's say you had a class size of 30. Now, class
number isn't consistent over time, ranging from one to however many you wanna take later on. I'm gonna say... 45, as a low estimate. That gives you 1,350 acquaintances. Arguably, you'd know these people better than your one-week-stands. You spent a whole year with them, after all, even if you didn't give them your full focus.
Now somehow, I don't confuse random strangers I meet with kids I knew in high school. Even my peers that I spent hours and hours of my time with don't make reality fog up for me.
Now, there is a case where reality fogs up for me. It's pets... Every time a pet annoys me, I cycle through all the names of my pets cause I'm stressed and
they all do the same shit. Uh... Well that's that.
Unless your character is dating all these people at the same time, it should never, ever be an issue. They aren't spending enough time with a single person to have that person be central to their mind. And if they ARE getting hung up on one person, then it's because of that ONE person. So then, it's not about quantity.
Following through on that, if your character is easily attached, and ends up having a large number of
significant relationships...
Sorry, I didn't sleep.