The Gospel Coalition on friendship

Here's what they have to say:

3.5. Friendship: The Remedy for Loneliness

Lest I overstate my case, it is worth digressing for a moment to agree that human beings are deeply relational, that in the absence of relationships we do experience loneliness, and that the Bible fully recognizes this. My point is not to deny our need for companionship, but to deny that sexual intimacy is the only or the necessary way in which loneliness may be alleviated. The Bible has a great deal to say about the longings of the human heart, but it is very striking to see how very rarely sex has anything to do with these longings being met. Almost all the Bible passages that speak warmly about human love do so in contexts where sexual intimacy is absent. God's remedy for human loneliness, according to the Bible, is not necessarily sexual intimacy, but friendship and fellowship.

Part of the problem in western societies may be that adults who are unmarried are very likely to live on their own rather than share accommodation either with other unmarried people or with a married couple. Loneliness is epitomized by coming back at the end of the day to an empty house or apartment. It is not so much the empty bed as the empty living space that deepens loneliness. We want sexual intimacy, but we forget that much if not all of our human desire for companionship can be met by shared meals, conversation, laughter, activities enjoyed together, and relaxation in the company of others we trust.