I'm not that pacifist rather than isolationist. In fact, in most of my games, I often play like Lady Six Sky will be supposed to be played: build your civ then don't care about your neighbor except if they settle in your living-room. City-states I was suzerain of are conquered? Don't care, I'll redirect my envoys elsewhere. A friend of mine attacked? Oh, too bad fo you, you should have prepared yourself. Someone try to attack me? I'll defend my borders, stack up happiness until the attacker see that it's pointless to attack me, then we make peace.
Then, after all of that, I sneak a diplomatic, cultural or scientific victory I was building in my core empire while everybody was doing "diplomacy".