How about if I get some DNA from Kate Upton, tweak it for high sex drive, low intelligence, low initiative, pliability, and a desperation to please, and then I grow a woman from it? Is she my friend?

If you design someone to serve your needs without asking that you serve theirs, the word "friend" is misleading. Friendship is mutually beneficial. I believe friendship signifies a relationship between two people that can be defined in operational terms, not a qualia that one person has. You can't make someone actually be your friend just by hypnotizing them to believe they're your friend.

Belief and feeling is probably part of the definition. It's hard to imagine saying 2 people are friends without knowing it. But I think the pattern of mutually-beneficial behavior is also part of it.