A “Fuck Close” is done if you sleep with the Target (Woman).
If you think your now in relationship with her or she will stay loyal by your side thats not always the case. Most woman have a stronger bond to you now but your actions immediately before and after the Fuck Close affect how your affair will develop.
If you don’t wanna see her again, dress up quickly, say confused “that was a mistake, i still love my ex” and be out of the door before she can answer you. That’s a clear sign.
If you want her as Fuck Buddy, explain her that you are absolutely no relationship-guy and always cheated on your ex-girlfriends so you don’t want to hurt her feelings. But you really love to see her again if she is okay with that.