The phrase "a deep regret" is correct and usable in written English.
It can be used when expressing a strong feeling of sadness or disappointment about something that has happened or a decision that has been made.
Example: "After reflecting on my actions, I felt a deep regret for the hurt I caused my friend."
Alternatives: "a profound remorse" or "a significant sorrow".
It's a deep regret, along with the fact that I am totally ungifted when it comes to jazz".
"Some of us find it incredibly hard to be parents, but live with a deep regret for having left our child," says Kahr.
And a few weeks later, on the steps of the Illinois statehouse, where he had first become a candidate for president, Mr. Obama expressed a deep regret for "my inability to reduce the polarization and meanness in our politics".
The battle did not make us just empathetic; it left us with a deep regret that it took a disease like this for us to understand how much we could learn from gay men.
In "Candy May," the first song on Alex Cameron's new album, "Forced Witness," from September, he sings, "I live with a deep regret of what I do on the Internet".
"We can stand alongside the federal law enforcement community in saying just as they felt a deep regret and sadness over the death of Randy Weaver's family, so we also feel a deep sense of regret and sadness over the death of Judge Lefkow's family," Mr. Roper said.
At the end of our week this summer, we felt a deeper regret for leaving, as if we were walking away from a friend.
And for all those things I have a very deep regret.
The failure by police to investigate the hacking of the murdered schoolgirl Milly Dowler's phone was unacceptable and is "a matter of deep regret", an internal investigation has concluded.
Ms John added: "It is a matter of deep regret that a child died in these circumstances.
The prosecuting body confirmed there were similar opportunities to bring a sex abuse case in 2002 and 2007, and that the Director of Public Prosecutions, Alison Saunders, said it was a matter of "deep regret" that a prosecution as not brought.
