People come and go in your life for a reason. Sometimes for a day, a season, sometimes for a lifetime. If you know for what reason that person is with you, you can learn something from it. When someone appears in your life, it is usually because you have expressed a need, consciously or unconsciously. People come to help you in trouble, guide you with support and help you physically, emotionally or spiritually, to grow as a personality and for the development of your soul.
Just at a moment, a person says or does something that breaks the relationship. Or sometimes a beloved person dies, sometimes they go their own way again. Sometimes they turn against you and force you to take a stand. What we have to realize is that our need is met, our wish is fulfilled, their work is done. The unconscious or conscious request you made has been answered and now is the time to move on. Some people come into your life for a while, because it is your turn to share, grow or learn. They bring you an experience of confusion and pain, of peace or of sorrow, they make you laugh or cry. They can teach you something that you have never done or have not experienced before.
Relationships in your life teach you life lessons, through which your soul can grow in consciousness. It is the intention that you recognize, accept and learn those lessons to deal with the experiences that you thereby experience in your life. Therefore, love those people and make use of everything you have learned from that relationship in all other relationships and situations of your life. Forgive the person if he or she has hurt you, or is still doing it. You do not have to accept his or her behavior for that. Remember that there is a "higher" reason for this, which you often do not recognize when you are in a situation that hurts you and makes you desperate. If you look back later, you often know what the meaning of that situation is for you, what you should learn from it. Then you might be grateful that that person was there, whether for a day, a season or for the whole life.