I'd like to know this too. I've never heard of it, but it sounds like something I habitually do. Maybe it's trying to attract someone with resistance, like prodding. I've always used this tactic because I'm highly selective of the opposite sex. It seems too easy to wind up in bed or get beaten down so hard that I can't recover, so I'm order to test the opposite sex I advance slightly, then withdraw, then advance, then withdraw, to deliberately test their patience. It never works. It's probably a bad form of manipulation. I get called a homosexual or an old man all the time for doing this.
It might also mean that someone is advancing at an angle to outflank and disarm someone's defenses who does not want to be advanced upon. It could be a form of rape.
Whatever it is, it sounds like an attempt to get something that someone doesn't want to give, a sidestepping of outright consent. It might be a tactic used by someone who is inherently shy, with low self esteem, and cynical, or it could be a rape tactic, as it sounds like it is obviously shady.
I don't really know what fractional seduction is I'm just guessing based on those two words and my own ideas.
If anyone knows what it actually is, please answer. I'd like to know too.