Many experts have described healthy friendships. Most of the secular sources describe them more in terms of what you can get out of the relationship. The Bible describes Christian friendships that are about how you can love the other person like Jesus would do. (Phil 2:1) In fact, scripture says, "This is my commandment, that you love each other as I have loved you. Greater love has no one than this, than to lay down one's life for his friends." ( John 15:12-14; Ruth 1:17) This is ultimate sacrifice Jesus made for His friends.
It's About Jesus God made us to be in relationship with each other, to help, and to teach each other, to have fun together and to tell each other the truth so that we can grow in our faith (Gal 6:1-3; Matt 18:15,16; Prov 27:17). A healthy Christian relationship has Jesus at the center to provide the unconditional love we are not capable of on our own. And they include honest feedback to each other given with the gentleness of Jesus. (Matt 18:18; Prov 27:17)
Guard Your Heart Focusing on how to love your friends does not mean you receive nothing in return or are abused in the process. He made it clear that He expects those in body of Christ to take special care with each other. But, He also makes it clear that while you are to love everyone, He doesn't want you to be close friends with people who chose Satan over Him. (Matt 7:6; 15:17)