Bro... picture this size difference between a man and a woman, now give the man a gun, now threaten the woman's current lover. Do you not see how he has no choice but to go along to get along?
The man wouldn't be in that position if he had removed any possible threats to be with his partner
We live in a society. You can't just "take care" of people at a whim. Theo is a law abiding citizen, he doesn't want that kind of help.
Indeed, Theo is a law abiding citizen, but have you forgotten he works in a law firm and is a lawyer himself? Sure, dealing with Gunner is already hard thing to deal alone, but he's capable with dealing at least a case against that man. It's his reluctance and hesitance that's holding him back from actually freeing himself from the toxic cycle he had grown used to with the man he once loved. Theo wanted to believe Gunner would change—that he would do it for the sake of their future because it didn't matter whether Gunner had money or not. It was Gunner's sincerity when they were young that drove Theo to grow false and lingering hope, because he still hasn't fully accepted that Gunner won't leave the dirty work-life K put him in.
More or less, it's his lack of security and trust that puts him in the situation he's in. And that issue is slowly being healed and taken care of when Theo's with Dylan. The blondie isn't as innocent, but he's the one that doesn't bring Theo the feeling of being suffocated in such a repeated routine.
no shade towards Theo, but man, he needs to grow some back bone