Looking back, did you establish an emotional connection with the girls as well? If they are just attracted to you but not comfortable, they might get buyers remorse/regret later, because it can make them feel like a 'slut' for sleeping with you that easily.
I usually lay my dates/targets the first or 2nd night if i'm just looking for some action (if i like them I wait a little longer), and I try to make sure I establish somewhat of an emotional connection as well. (but then again, some girls are just in it for the lay.) The ones that are looking for more will always come back if you have an emotional connection as well as the attraction.
Her text: to me it seems like she regrets it, because she doesnt want the other guy to find out.
I dont know if you've lost her, because she could be careful about the other guys feelings as well.
Right now I cant really think of anything you could reply besides "It will be our little secret

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