Similar Values,
A True Friendship,
Mutual Trust,
Mutual Respect.
Because those are foundational and don't change over time.
The usual list is good communication, mutual interests, and good sex... which can't be "foundational" because they change over time.
And Meth.
Good communication is necessary, butI would put mutual interests way down on the list.
It’s good to have some so you can enjoy doing some of them together, but I think it’s very healthy to have some that are not. I think each person should have some interests that get them out with their friends. It keeps them well rounded and from getting too ingrown and dependent on each other.
I don’t know how to explain it, but I think maybe it keeps a person more well rounded.