Solid relationships are built on open lines of communication. But when it comes to talking about sex, even the most candid can clam up. Who wants to hear the dreaded “no”?

Enter Luhvah, a new app created for couples that seeks to solve their carnal woes by boiling desire down to a science.

The impetus is Dan Waters, or rather, his wife. The chief executive of Open Island, a mostly Richmond-based start-up, asked her a particular question. “Her response was ‘definitely, no,'” says Ernest Hawkins, the company’s chief design officer.

“In fact,” Hawkins says, “she told him she despised this kind of conversation and wished they didn’t have to have it.”

Luhvah allows partners to rate their desire by number and send a discreet, naughty-if-you-want message by way of a “nudge.” When partners have similar do-you-wanna numbers, ding ding ding: Both are getting lucky.

“It seemed like too good of an idea,” Hawkins says. “We thought there was no way it hadn’t already been done, but after days of research found nothing like it.”

They named the app after a skit on “Saturday Night Live” featuring a sweaty and amorous hot-tub exchange among characters played by Will Farrell, Jimmy Fallon and Drew Barrymore. But no worries on your conversations getting out, the company says. To preserve privacy, messages are erased after being read.

There is a plethora of dating apps for singles, says Donnie Schemetti, the company’s chief marketing officer, but there’s been no platform for monogamous couples till now.

“There’s a market for it,” he says. “There are so many people out there settling down, and we want to help them communicate a little better.”

After making the free app available in the iTunes Store last month, the company reports that it’s averaging about 20 downloads a day from all over the world. Not bad for a small company with limited funds, employees say.

While soliciting feedback about the app might be difficult given the preferred end result, users have been forthcoming and grateful. “One user said she likes it because it has a different alert tone, and when she hears that noise it’s like an out-loud secret that only she knows about,” Schemetti says. “In a public place, she can have an intimate moment” — or at least the promise of one.

It’s also paid off for Waters, the man who started it all. “Without giving up too much,” Schemetti says, laughing, “our president said it has eliminated the argument about sex.”