在一起了却发现你不快乐
[zài yī qĭ le què fā xiàn nĭ bù kuài lè]
This suggests that even after getting into some kind of close relationship whether friendship romance marriage or else realizing that the counterpart does not feel joyful in this bond which reflects deep concern empathy understanding toward each other's true feelings while also expressing helplessness over the complicated human nature.