amicable

Amicable means friendly and without ill feeling. Two people who have parted, and are not going to make a scene about it.

The word lives in one phrase above all: an amicable divorce, an amicable settlement, an amicable separation. That is telling, since amicable is used precisely where things could have turned nasty and did not. It describes relations rather than people, so you do not usually call a person amicable. Its root is Latin amicus, a friend, which also gives English amiable, and amiable does describe people.