God tells us to make loving others a priority in our lives, especially those who give us the hardest time. Though this person may frustrate you, maybe even question all that you stand for, you understand that you must love him/her anyway. These are some strategies I have used in my daily life to love the very people who occasionally make me want to rip my hair out.
1. Listen.
Try to care more about what the other person has to say to you. You may find he/she does not understand what you are trying to get across, but you also may find you do not understand the message he/she want you to hear either. Move past right and wrong. Relationships are not about who comes out on top, only about remaining in the relationship you care about. Try to figure out if your pride is more important or the relationship, and if you pick your relationship: Throw away pride; throw away stubbornness. Genuinely hear what the other person has to say. Then respond after completely understanding how he/she feels.
2. Accept them for who they are.
Every person is different. What works for one person may not work for another. Accept the ways he/she does not want attention. Find a way to support and love them. Find those small pieces of them you can support, whether it be a shared interest or hobby, then slowly find more and more ways to support that person.
3. Give them space when needed (don't be Brenda Song).
Sometimes you will not get along with them. Make sure you maintain a bond, but give each other space when problems arise. Consult one or two other people on the conflict. Do not be afraid to ask for help.
4. Try to encourage them
Try to encourage them with small acts of kindness. Leave them a sticky note with a nice message or bring them some ice cream. Show appreciation for their presence in your life. Sometimes the most impactful actions are the smallest ones.
5. Try to pray for them.
One of the hardest things to do is love those who give us a difficult time. Pray for problems he/she may be having, whether it be for their family or school. Lift them up, especially if it has been a difficult day. Praying for those who give you trouble or irritate you will help to focus on goodness rather than hatred. Give God all the problems you are unable to fix in the relationship and ask Him what you can work on.
You've decided to keep this relationship in your life. Continue to feed it by being patient and loving them in as many ways as possible. Discern between the problems you can actively work out and the conflicts in which you must move forward from. Remember that it is not about who is right or wrong, just that your friendship continues on.