So I've also been trying to proc this scene for a little while, and after finally getting it and trying it on a few different characters:
You need a lot of strength, probably 95+ like the other user said, so Womanly characters can't get the full scene. They can still rip blouses, though.
It also depends on which rival you get. I don't know how many variants there are, but I've gotten the full scene with the anti-bully rival and the prudish rival. I also tried it with the bombshell rival and the hardworking rival, but the option to rip their tops never showed up, despite my characters meeting the requirements. So you don't explicitly need Bitchy like some people were saying earlier, but it does help in getting the right rival, since it's completely random which trait they'll hate you for.