Girlfriend tells me that she needs constant male validation. How do I handle this in a responsible manner?

I've caught be girlfriend texting and leading on other guys to get attention. She has made no plans to meet up with them it's only been purely through text. However it still upsets me and I feel disrespected. I have expressed this too her and she has stopped texting dudes for now. She also talks about how she misses her ex but also how she hates him cause he found another girl. Im 22 and not too sure how to handle this kind of behavior thats in the grey area of boundary crossing because she's technically not cheating. Any advice is much appreciated.
Girlfriend tells me that she needs constant male validation. How do I handle this in a responsible manner?
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