Why doesn't he just look for someone else? Or does he only know Wolf? Or are they friends?
Wolf does the art in addition to the coding, and is a big deal in the Chinese adult game scene (from what I've heard at least). It might be difficult to find another developer in China who Tentacle is willing or able to work with.
Wolf doesn't do the art. Wolf doesn't do art at all. He's hired someone for Cursed Armor 2, and the Tentacle dude hired someone else for Fallen Valkyrie. Plus, if you looked at the Patreon, you'd have noted that the Tentacle dude did several posts with art that was being worked on or planned to be added to the game even while Wolf was fully busy with Cursed Armor.
The problem isn't the art. The problem is that they're both Chinese. Porn is
illegal in China, in all of its forms. It's illegal to make and it's illegal to sell it. This means that it's risky to try and change partners in this business. Not only is it hard to find someone to trust, but if the Tentacle dude broke things off in the wrong way, Wolf could set the government on him. Obviously, this applies both ways, but the end result could easily be not pretty.
I do believe that the two of them are friends, or were, it's hard to really gauge their relationship based on just Patreon posts. Wolf helped the Tentacle dude with the previous game he made too, so for all of Wolf's issues, the bastard
does usually keep his word in the end. Even with his ridiculous anti-piracy mania...
However, even if they weren't friends, the issue is that as a Chinese H-game developer, you have to be very careful. I've seen one group that had to literally delete all of their pixiv and so on accounts at one point to shake off the government.