depends entirely on your relationship with the girl in question
Some girls are legitimately going to want you to be happy and succeed,
some girls won't really care but won't lift a finger to help you either,
some girls are sociopaths who actively want to keep you on the hook and drain your attention and resources forever and will actively work against you getting anywhere with anyone else if they can help it (some will be less blatant about it and why than others)
Some girls think you're a loser that shouldn't have anyone,
others will actively sabotage your game for no real reason because they're b!tches and haters
Only you know what kind of person she is and what your relationship with the girl in question is, but I think it's a huge risk if you don't know she's on your team