It was just a year ago that David Nail picked up his phone and texted an early recording of his new single "Best of Me" to a group of folks that included his wife, Catherine, his parents and his in-laws.

Everyone replied, except one person.

“He kind of keeps his cards to himself,” Nail tells Taste of Country during a recent interview about his father-in-law’s subdued reaction to his heartfelt new song. “I thought that maybe he was just not in the right headspace at the time to listen to it, or something.”

The stoic man did take a listen to the most recent work of his Grammy-nominated son-in-law — a piece of work that could be the Missouri’s native’s most beautiful yet.

“He's told me different things like ‘it's one of my best’ or ‘it's so well written,’” Nail explains of his father-in-law's feedback. “Knowing the man as well as I do, those types of one-liners are huge (Laughs). It’s like the equivalent of somebody else saying six or seven lines.”

Nail has been striving for that kind of approval for more than a decade. It was nearly 14 years ago that the multi-Platinum singer-songwriter sought out that same man's blessing when he wanted to ask for his daughter's hand in marriage.

And that's what "Best of Me" is all about.

"I mean, obviously this song is about (Catherine),” says the "Whatever She’s Got" hitmaker. “But I really wanted it to be kind of a tribute to my father-in-law, too, and how much I really wanted to get his approval."

"It was more than just wanting his blessing — I really wanted him to believe in me. I wanted him to believe in us.”

Nail dated other women before meeting Catherine, of course, but he never imagined talking marriage with anyone’s father, until the moment he met his future wife.

“When I began having those feelings about having that conversation with Catherine, that's when it got real,” says the star. “That all happened very quickly, and it was something I was very passionate about.”

Infusing this passion into “Best of Me” was something Nail says became a bit of an obsession — he even when so far as to release the song earlier than anyone on his team had planned.

“I think a lot of times when you write something and you don't record it right away, sometimes it can kind of fall into that group of songs that no one's ever going to hear," Nail says (he plans to drop "a slew" of new music in the coming year). "But (‘Best of Me’) was one of those that just kind of kept resurfacing for whatever reason. This song is about as hooky of a song, lyrically, as I've ever written."

It has even made him cry once or twice.

"I'm the emotional, sensitive person in our relationship," he admits with a chuckle.

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