Example: John really gets on with Daniel, but he fakes it with Daniel’s son.
John gets on really well with Daniel, but he plays along with Daniel’s son. I don’t really know Daniel, so I understand that he is tired all the time.

Are the feelings in your head and mind about your parents? At best, though, tolerate, put up with, endure, stomach imply a neutral observable behavior. But in the situation you ask for, John is acting like he has a positive relationship with his son. He gets on with him, albeit mildly.

To emphasize the artificial performance of the positive interaction, I suggest the phrase “fakes it”. Is he so good at convincing my son that he wants to raise my son?

Is the phrase “plays along with” helpful for weaker interactions? David is obviously arguing with John but he isn’t convinced he is being able to find a place in the world while he is battling Daniel for

the father. This suggests that John’s apparent “getting on” with the son is not as strong as his “getting on” with Daniel, but it is still better than neutral.