It's questionable, I think. "Corruption" has a pretty negative connotation, I think. Like, you make the person less-than in order to make them yours. The tag says:
MC starts off as just a father. He recognizes that his three girls are attractive, but he doesn't lust after them. He wants more than anything to simply be a father for them, a man they can always depend on. Arguably, he is Pure.
Becca, the oldest, has been in love with MC since she first saw him. Now that MC is no longer married to her mother, Becca plans to be with him. She is arguably the Corruptor.
Lilith, Becca's little sister, has major daddy issues. She flits from relationship to relationship, giving her all to the guy she's with only to be betrayed and abandoned time and again. Becca feels that MC would be the perfect man for Lilith; able to dominate her in a loving way - gentle maledom. Becca has "a plan" that has the end goal of having her, Lilith, and MC all in a relationship and she is manipulating Lilith, and to a lesser degree MC, in that direction. Becca's machinations have helped Lilith and MC grow closer (Becca knows what Lilith needs in order to see MC as a dominant figure), as well as helped MC realize that he does want more than a parental relationship. So far, however, he's not been willing to risk losing what he has to get there.
All of this could be seen as Corruption by Becca on Lilith and MC in order for them all to move beyond their Pure father/daughter roles.
Meanwhile Abigail is also in love with MC, and certain revelations have made it possible for her to see MC as a potential romantic partner. She's been independently "corrupting" MC to bring him around to seeing her as more than just a daughter as well.
So, yeah it's technically corruption, but as I mentioned above, it's a wholesome corruption. Nobody is being broken and turned into a sextoy like most corruption games; they're all just being changed from family into lovers.