There are plenty of cases like that. I personally know women who were left right after the guy finished his graduation. There was a girl in my Uni who was rich, beautiful, younger than the boyfriend, traveled abroad while he was from very humble beginnings. Both were black and physically compatible and going to the very same college. And, then, after so much time, they broke up, specifically after he graduated. I believe it was her first boyfriend, since she started dating him in day one. And she was very very young, like 18 or 19.

There is another case below:

https://www.lipstickalley.com/threads/reddit-husband-finally-graduates-at-30-wife-finds-out-he-plans-to-leave-her-after-graduation-because-he-doesnt-need-her-anymore.4715080/

So, why do men do this? Do they deliberately plan this or what?

And these are only two cases. I, personally, know A LOT OF cases like that and I have seen a lot in internet. If you digit "never build a man" and "starter girlfriend" in Google you will see a lot of results.

So, with all this evidence, the concept of men being the fair sex is wrong? What are your opinions on the matter?