It’s always unsettling when an important relationship starts to “shake”. While you didn’t give any details, I will try to respond in a general sense, based on God’s Word.

The first thing you must decide is, “is the relationship worth saving?” Sometimes people move away from the relationship due to changes in beliefs or other pursuits. In that case, trying to hang on to what you used to have could be more about fearing change. In this case, letting go in love and truly desiring God’s best for them is the way to go. We see the best prescription for keeping in God’s will is found in His definition of love in 1 Corinthians 13. Verses 4-7 seems best for your situation, “Love does not insist on its own way; it is not irritable or resentful; it does not rejoice at wrong-doing, but rejoices with the truth. Love bears all things, believes all things, hopes all things, endures all things.” While it may be your way to want to keep the relationship the way it was, love would accept and allow your friend to go their own way, with your love and prayers. Even if you don’t think what they’re doing is a good choice, your love and caring will keep the door open for a relationship, even if it’s different from what you desire.

If the relationship is mutually desired, then it’s good to seek after God to find out what He says is best to repair the relationship and return it to His will. But be prepared. Walking in God’s love may require you to do the hard part! I have found that when I face a challenge in a relationship, rather that getting a justification about the other being wrong, God usually tells my heart what I need to do to fix it! Matthew 5:23-24 gives an example of dealing with this, “So if you are offering your gift at the altar and there remember that your brother has something against you, 24 leave your gift there before the altar and go. First be reconciled to your brother, and then come and offer your gift.” We must take responsibility and be the “hero” if we want God’s best in the situation even if it means sacrificing “our right to be right!”