do you think its easier to get a girl you already been with both sexually and in a relationship back then to get a girl from thin air or you think its harder i mean you could remind the girl about all the good times you had and go from there right i really want this girl back but i don't think she likes me anymore

From my understanding, it's a little of a double edge sword and it depends greatly on the situation. Why aren't you together anymore/How did it end? How long has it been since then? How much have you changed? How good was the interactions between you two when you were together?

If, for example, it was your old high school crush, and you dated for a while before she decided to just be friends, then meet for the first time since graduation, I'd say chances are fairly level, if not a little better since you already have some amount of comfort. You'd still have to build attraction, but in a different way from just meeting a girl. If you've improved your game extremely, or actually found some, then it'll be substatially easier. The down side is you have to overcome her preconcieved notions of the person you once were.

I had to do something similiar, but not with a target. I met some of the best friends I had in high school again for the first time since we lost contact, one of which was a girl dating my buddy. Since he was a friend, I only pulled a minimum of game with her (honing the skills, as it were), but found that she only saw me as the nerdy, quiet boy I used to be, rather than the awesome man I've become.

If this is a somewhat recent breakup, however, and she ended it...well, it'd be better for you to go to the thin air option, at least for a while. It's much the same as dealing with a woman that's already not interested in you. Disappear for a while, reinvent yourself a little, and then come back with a woman on both arms. Personally, I don't think it's worth the effort, but that's just me.

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"You have to be a man first, before you're a gentleman." (John Wayne, McLintock!)