How well do you know your significant other? Would you trust him or her with your money? How about naming that special someone as beneficiary on your life insurance policy?
At a time when relationships can increasingly be described as "it's complicated," some experts are advising a decidedly unromantic move: subject your sweetheart to a background check.
"In business, we often do what we call due diligence. And that is, just being prudent about understanding who it is that you're doing your business with," said Chris Marquet, president of investigative services at SunBlock Systems, a Reston, Virginia, consulting firm. "The same really should be true in your relationships."
A lack of due diligence can be costly. In extreme cases it can even be deadly. As told on the latest episode of CNBC's "American Greed," California utility worker Linda Curry trusted her husband, Paul.
"He's always thoughtful. I mean, he's a nice person," she told investigators.
But soon after, Linda was dead, the victim of a cruel plot by her husband to gain her insurance proceeds.
Marquet says it is all too easy to miss the warning signs of a partner who is not quite who he says he is.
"Love tends to blind logic. And so when you're in love, or you're with somebody, you want to see all the good," Marquet said.
Compounding the problem: couples are getting together later in life — Linda was 45 when she met Paul — and more than ever, they are meeting online. A study published in the Proceedings of the National Academy of Sciences found that more than one-third of married couples in the U.S. began their relationships on the internet.
"Nowadays with all the online dating and people meeting up and people moving around, it's easy for somebody who really has ulterior motives to, you know, create a persona," Marquet said.
Marquet, a veteran private investigator, says he got so many requests from friends to investigate their partners that he decided to start a business on the side aimed exclusively at couples. The company, Check Out Your Partner, is now 10 years old.
A bit of due diligence on Linda Curry's part might have turned up the fact that Paul did not have the degree in nuclear physics he claimed — in fact he did not have a college degree at all. Or that his marital history was not quite as advertised.
Of course, most of us do not have to worry about marrying a diabolical killer, but Marquet says there are still instances that cry out for some investigation.
"They're saying things that are inconsistent, or they're telling stories, or they're disappearing for periods of time and you don't know what they're up to, you might want to dig a little deeper," he said.
If you are one of the millions of Americans who use an online dating service, do not rely on the sites to vet your potential partner. The major services all carry disclaimers.
"It's up to you to research and do your due diligence," says Match.com, in an entire section of the site devoted to safety.
Dating service eHarmony cautions that while it does monitor for unusual account activity, "eHarmony does not conduct criminal background checks at the time an account is registered."
Of course, running a background check on your partner can throw a wrench into your relationship should your partner find out. But Marquet says it may be worth the risk.
"Wow, you did that on me? You know, I can't believe you don't trust me. I can't believe that you would do such a thing. Yeah, that's a tough thing to overcome," he said. "But sometimes, the truth is the truth. If there is a problem, or there are issues, and they're not being forthcoming, and you literally have to go that far, it's defensible."
Besides, there nothing that says you have to check out your partner behind his or her back. Still, if you feel the need to run a background check on your significant other, should you be with that person in the first place? Marquet says that is a false choice.
"Oftentimes when you're going out and you're on the dating scene or whatever, your tummy will tell you pretty quickly. Yes, no. Boom. You move on. But sometimes it's not so clear," he says. "I'm not just protecting myself and my feelings, I've got family, I've got an estate, whatever."
We will never know if a simple background check would have saved Linda Curry's life. After all, it would take another 16 years for authorities to finally crack the case. But trading a little romance for a little bit of research might have at least given her a fighting chance.
Go inside Paul Curry's toxic plot, and see how authorities finally solved the crime, on an all new episode of "American Greed," Monday, June 19, at 10 p.m. ET/PT on CNBC