Why are millennial men so obsessed in dating 18-25 year old woman?

One of my best friends she is 30 about to turn 31. Her boyfriend 29 of 8 years left her for a stupid 21 year old. I just can't understand. They live a good woman that is capable of being a good wife and yet this guy lives her not caring about her at all. What is wrong with Z generation woman that don't seem to have respect over other people's relationship. My head just can't seem to understand. Love is painful it's all I can say.

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Weird thing apparently now a days with guys my generation millennial if a girl cooks for a guy or she runs favors for him apparently we are going insecure.
Why are millennial men so obsessed in dating 18-25 year old woman?
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