What's the noun for amiably? Here's the word you're looking for.
amity
(literary)Friendship. The cooperative and supportive relationship between people, or animals. In this sense, the term connotes a relationship which involves mutual knowledge, esteem, affection, and respect along with a degree of rendering service to friends in times of need or crisis.
Mutual understanding and a peaceful relationship, especially between nations; peace; accord.
“Natural amiableness is too often seen in company with sloth, with uselessness, with the vanity of fashionable life.”
“But when she meets an unusual customer with an affinity for French films, his beautiful smile and amiableness melt her.”
“Mr. Knightley expressed his disapproval of Frank's behavior and Emma's vision of him by contrasting what he called French amiableness with English amiableness.”