同床異夢
dou.shou.i.mu
Literally: same – bed – different – dream
Alternately: Even though two people share some external thing in common – where they live, where they work, their situation, etc. – they have different goals, priorities, or ways of seeing the world.
Notes: This phrase comes to us from the writings of 12th-century Confucian scholar Chen Liang.

I guess it’s also… the title of an obscure TRPG (Tactical Role-Playing Game)?