Any movies that's about the guy/girl desperately trying to get their ex back?

Hey guys, pls I need your suggestion. I'll be doing an online campaign
to promote products about "how to get your ex back."

I'm doing my research to understand the subject. And I'm looking for
couple of movies that shows two lover in who are completely in love
with each other, then they break up, then the guy/girl(who got dumped)
being miserable --- are trying to get their ex back etc.

Any movies like this you could suggest? Thanks in advance.