That's your sticking point. You have friendzoned yourself by the 3rd or 4th date. You shouldn't talk about past relationships whether yours or hers. But you're doing something right because you can get the girl to have a date with you.
You need to sexually escalate. Try this for some 10 dates and tell us if it works for you,
esp-model-of-escalation-vt97891.html
It appears to be working for me on my first and second test. Who knows? It might work for you.

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Approach. Open. Escalate. Isolate
Here are my two essential rules on texting that will save you tons of time and money:
general-questions/topic137931.html