Guys, Do you start talking to "new girl" before you've fully left "old girl"?

I've seen so many guys do this and I don't know why. They feel their current relationship is in a slump and suddenly start calling or chatting with another gal... He'll convince himself "we're just friends" but the way he's talking to the gal is very exploratory and a bit personal/nosy. And the funny thing is that there's nothing the new gal can do about it except to just not address the guy at all. There's no saying, "Aww, your girlfriend is such a nice person, [blah blah], and you two are so nice together [blah blah]" because all he'll think is "she gets me" because he's thinking that the old girlfriend just doesn't get him anymore.

And he could be with her for 1... 3... 5... even 10 years. Why throw that time away? I don't get it.

One guy friend literally left the country bc he'd done that to pretty much every woman he knew here. He's now happily remarried in his new pace.

Another guy I know just started snooping this week out of the blue. I don't know why. I asked him to help me with one small thing once, we swapped numbers for that and were silent till suddenly he reached out. We chat about books mostly, but suddenly he asked what's up for V-Day? He knows I'm single so I give a generic response and ask what he and his gal are doing... falling right into the trap. "We're not doing well, so probably nothing." It's flu-and-cold season so I reply "Feel better." (I don't want to get in the middle of anything.) And that's when he gets into how the relationship is dying... they're not on the same page... And of course I try to talk him out of it bc they've been together for a WHILE, but she apparently just doesn't get him anymore.

Going to shut down the association so I'm not "aiding and a-bedding"!

So I guess I have TWO questions for these types of players:
1. Don't you KNOW a gal isn't compatible with you from the get-go? Why waste HER time?
2. Do you start chatting up your next point of interest while you're still in your current situation?

Guys, Do you start talking to "new girl" before you've fully left "old girl"?
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