Credit: Adam Taylor/FOX Photo: Hannah Burley Returns from Afghanistan in Season 6, Episode 2: "The Couple in the Cave"

If there is anything that can drive a wedge into a relationship, it's secrets. Too bad Booth doesn't know that, because he's been keeping some doozies from Hannah. We get it; dodging enemy fire is better suited to a conversation like, "What's your favorite color? Do you have any pets?," rather than, for example, "So, once upon a time, I was in love with my partner and killed people for a living."

Since Booth was so eager to have Hannah move in with him, he probably should have brought up a few of the following itmes before he gave her a key.

He Hates Clowns (and Even Shot One)
Okay, we can't really see Booth's coulrophobia coming between Hannah and him. Unless of course Hannah hires a clown for Booth's son Parker’s birthday. Now, the clown shooting… yeah, that might make Hannah wonder exactly what is going on in her man's head. After all, the "clown incident" (Season 2, Episode 13, “The Girl in the Gator”) forced Booth into therapy, first with Dr. Gordon Wyatt and then Lance Sweets. And Sweets thinks Booth and Brennan are wildly in love with each other. So actually, the subject of clowns could be a problem. See how one thing just rolls into the next when at first you practice to deceive?

He's Got a Gambling Problem
Funny how many secrets Booth easily told Brennan, but when it comes to sharing his past with Hannah, things just seem to slip his mind. Booth went to Gambler's Anonymous to get help with his problem, but when is he going to tell Hannah that? What if she suggests a romantic weekend in Vegas? Or says, "I'll bet you five bucks that the Redskins will win this weekend?" Booth needs to come clean, before he accidentally falls off the gambling wagon.

Credit: Adam Taylor/FOX Photo: Brennan Diagnoses Hannah in Season 6, Episode 5: "The Bones That Weren't"

He Used to Be a Sniper
Is there any good way to tell someone you used to be a killer? Granted, Booth was a law-abiding, hero-for-your-country kind of killer, but a sniper nonetheless. Normally this subject would be next to impossible to bring up to someone you are dating, but since Booth and Hannah did meet in a dangerous part of the world while he was doing dangerous things for the United States government, it should have been easy to work into the conversation. The perfect time would have been right after he saved Hannah's life: She'd have been in the afterglow of seeing this hot guy in all his bad ass glory, and all he’d have to say is, "What a coincidence: I used to snipe for a living!" Too late now. We just hope Temperance doesn't blurt out the info by mistake.

He's Trying to Atone for His Kills
It's one thing to be a sniper and another to be a nice Catholic boy who was just trying to do his duty to his country. Booth's Catholic beliefs motivated him to join the FBI: He is trying to catch a murderer for every person he killed. Now, in the act of trying to lock away bad guys, he's also had to shoot a few more. So he's got his atonement work cut out for him. Why bother with that anyway? Because it's an essential part of who he is. Hannah might think it's noble or kinda wacked, but he'll never know unless he tells her.

He Recently Declared His Love for His Partner
Hannah has absolutely no jealousy with the relationship between Booth and Bones, except that they seem to have some fun adventures, and she misses her wild and crazy "running from gunfire and baddies" days. Still, if his new girlfriend were to learn that a mere year ago Booth admitted to Bones that he was crazy in love with her, Hannah might start to wonder if the guy has rebound issues — and she may feel differently about getting all chummy with her former rival. Sure, Booth said Hannah isn't a consolation prize, but you know that's exactly how she'd feel. This little secret should have definitely been made public before Booth asked Hannah to share his address.

We’ll definitely be tuning in when Bones returns on January 20th, 2011 to see if Booth spills the beans — or if someone lets the cat out of the bag for him.