The phrase 'thorny relationship' is correct and usable in written English.
It is often used to refer to a relationship which is difficult or complex. For example, "The negotiations between the two countries have been hampered by a thorny relationship that has been built up over many years."
This thorny relationship between the markets and the Fed – "I love you!
Experts believe Taiwan's thorny relationship with Beijing may also prove a severe challenge for its new leader.
It is Himes's attempt to record his thorny relationship to an oppression other than his own that accounts for some of his most troubled and troubling writing.
Eight years ago, Clinton developed a thorny relationship with African-American leaders here amid a grueling and bitterly contested primary with Obama that was roiled by racial tensions.
He describes the sometimes thorny relationship between fathers and sons, like that of the golfing legend Claude Harmon and his son, Butch.
As a company self-consciously focused on creating media content, Disney has long had a thorny relationship with distribution companies like cable operators.
And, in an unexpected plot twist, the study, which surveyed 1,611 men and women age 18 to 23 in the Miami area, found that thorny relationships take a far greater toll on men.
But Mr. Gates has a thornier relationship to many old objects than most people do.
Teresa Fazio, who was a Marine Corps officer, read an excerpt from her memoir describing a thorny romantic relationship begun in a mortuary in a military camp in Iraq.
She said that these days the gods were more likely to be consulted on thorny personal relationships than on physical illness.
The Davis affair was particularly thorny for the relationship between the two spy services, since Mr. Davis's covert group in Lahore had been assigned to gather intelligence about the militant group Lashkar-e-Taiba, which for years has been nurtured by the ISI to carry out attacks inside India.
