There are a few simple methods to tell whether or not a friend truly has your best interest and friendship in mind:
1. Secrets: Sharing secrets with one another is a sign of trust. Does your friend share secrets with you? If so, then they see you as trustworthy and confide their skeleton to you. However, do you share your secrets with this friend? Do you see them as a trustworthy source, or are they telling other people your secrets too? A friend who is spilling your private life to your other friends isn’t a very good friend at all.
2. Advice: Giving and taking advice sincerely is the sign of a true friendship. For example, if you tried to tell your friend that her boyfriend was cheating on her, would she get angry at you for such an accusation or take your advice seriously because they consider you a dear friend with their best intentions in mind?
3. Forgiveness: No one is perfect and everyone screws up once in a while. True friends both recognize when they have messed up and also ask the other friend for forgiveness. If both parties can manage to forgive, then that is a sign of a true friendship.
4. Protection: A true friend will have your back at all times. It is one thing for your friend to tell someone to calm down and stop it if someone is yelling at you in a public place, but it is another thing entirely for your friend to stand up to you and tell someone to quick speaking poorly of you even when you are not around. That is the sign of a true friend who has your back.
5. Trust: A true friend is someone who you can trust with your most treasured belongings. For example, you can leave your boyfriend with your friend alone and not worry, you can easily loan them personal items, such as jeans, ipads, etc. and not be worried that they will be broken or never returned, etc.
Sources: Gaiam Life