Does this make sense to anyone?

The amount of girls I’ve seen purposely get pregnant, a relationship rescuing btw, not trying to trap him, only to break up with the guy during pregnancy is horrific, some have been 3 times. I don’t understand why a young girl, 18-21, would purposely get pregnant out of marriage, like if you two love eachother so much and want kids, why not wait? Can someone please explain why a girl would do this?