"sustaining friendship" is a correct and usable phrase in written English.
You can use it when you're talking about preserving or maintaining a relationship, or nurturing the bond between two people or groups. For example, "Strong communication is essential for sustaining friendship over long distances."
Faced with this dreary reality, single women getting up in years, instead of losing themselves in the quest to find Mr. Right, ought to focus instead on feathering their own nests — with pride, contented self-sufficiency and sustaining friendship.
Leigh Bowery and Freud had a mutually sustaining friendship that went on until just before the performance artist succumbed to an Aids-related illness at the end of 1994.
Back at Black Mountain he began a passionate affair with a fellow student, Cy Twombly, as well as developing a productive, sustaining friendship with another queer couple: the avant garde composer John Cage and the dancer Merce Cunningham.
Instead of trying to communicate what was so breathtaking about Hawking's cosmological studies, what the film-makers offer is a flat domestic melodrama about a woman's struggles to care for a disabled man, and about her sustaining friendship with a drippy choirmaster (Charlie Cox).
In alternating chapters the reader learns about Watson's brief, youthful service as a pilot during World War II and his harrowing experiences as a P.O.W., his postwar marriage to the nurse who accepted what torture had done to his "basic equipment," his religious vocation and sustaining friendship with a few fellow survivors of that terrible camp.
During this year, he began a long and sustaining friendship with V. F. Calverton.
But the pressure of sustaining friendships and maintaining high grades while managing swimming expectations is a lot for even Franklin's broad shoulders to bear.
Ridge, however, thinks matters are more urgent and suggests that I'm headed for loneliness later in life if I don't start actively sustaining friendships.
Mr. Buchan, who studied Persian and Arabic in Iran in the 1970's and later worked as a foreign correspondent for The Financial Times of London, does a vivid job of limning the interrogations and beatings John sustains, the threats of death and torture he endures, while at the same time conveying the sustaining friendships he develops with other political prisoners.
Recent research commissioned by Scottish Women's Aid has identified the dramatic impact that domestic violence has on the outcomes for children in these situations, with high levels of anxiety, the loss of personal belongings and familiar surroundings, trouble sustaining friendships and missing long periods of school.
Lindsay Anderson certainly had a flair - some would say a genius - for making enemies ("always the right ones"), and an even greater flair, if not genius, for making friends and sustaining friendships: the fact that "love was not enough" was part of the pain that characterised much of his estrangement from the world by which he found himself surrounded.
