get on famously
To have an exceptionally good relationship (with someone); to get along very well. I'm glad you finally got to meet my brother—I knew you two would get on famously. My grandparents have been married for over 50 years and they still get on famously!
get on/along ˈfamously
(old-fashioned, informal) have a very good relationship: My mother and my mother-in-law are getting on famously.