Emma Stone thinks friendship is key to a strong relationship.

The 'Birdman' actress - who is dating her 'Amazing Spider-Man' co-star Andrew Garfield - doesn't get to see her pals very often but says they are ''formative and key'' to her ''existence'' because they have been so influential on her.

She said: ''Friendships are very important. Friendship is the core of any relationship - whether it's a love relationship, a family relationship or a friendship.

''It's the most important thing we can be with each other as human beings - understanding one another.

''I've had hugely important friendships. There are childhood friends who are still a bit part of my life and people I don't see so much but they are still important too.

''As time goes on, you work with people or meet people socially who become mentors or true friends or love interests in your life, and all those people are so formative and key to your existence - as they say, no man is an island.''

The 26-year-old beauty also admitted she feels ''very protective'' about her personal life and wishes she cared less about opening up to people.

She told Psychologies magazine: ''For me, I value privacy so much and I understand why I need to talk about the work, the films and all of that but it's incredibly hard to reveal stuff about my life, so it makes me feel pretty boring and very protective.

''I wish I could just let it go and be like, 'Oh whatever' but I can't. I'm a Scorpio. Maybe it's something to do with that.''