First of all, allegedly G and Tay have been together for more than 10 years now (earliest pics in 2012). I would have thought any tension/frustration due to power imbalance, if any, must have hit boiling point and resulted in a breakup long time ago. While Tay's family is most likely not as wealthy as G's, I don't think they will happily and willingly let their son be in an abusive relationship, as you're alluding to.
But honestly, if this was a hetero couple wherein the woman was a beauty pageant or supermodel and the man was a super wealthy man, no one would have bat an eye, like that's how it's supposed to be. Why the difference now?
Also, we don't know exactly how involved Tay is in G's business ventures. I think pretty deep judging from his interactions with G's business associates.