REASON 1: They know they have to support each other — even if it's obvious one of them might fail. It happens pretty frequently on the show, but in "Princess Party" Mitchell protests when Cameron will not stop insisting that they allow Fizbo the Clown (Cameron's creepy clown character) to perform at Lily's princess-themed party. But Mitchell knows how excluded Cameron feels about it, so he lets him do it. Of course catastrophe ensues, but Mitchell knows he had to let Cameron do it. It's the same thing that happens when Mitchell decides he's going to build a life-size princess castle for Lily in the backyard, despite his inability to use tools (as in, he has no concept of nail gun safety). Though Mitchell does build a beautiful castle, he ends up trapping himself inside it in the process. Cameron and Jay apologize for underestimating him, even though they know they'll eventually have to pry him out.
REASON 2: They've accepted life's imperfections.
After same-sex marriage becomes legal in California, Mitch and Cam both want to be the one to propose, which is sweet in itself. But along the way they learn that even a marriage proposal comes with imperfections. "This is not at all how I saw the evening going," Mitchell says while they're stuck on the side of a road changing a tire. In a touching scene, which you can watch above, they reminisce about the other imperfections in life they've dealt with together.
REASON 3: They know when it's time to grow up. Cameron and Mitchell decide to have a grown-up night out with an old drinking buddy, Sal (Elizabeth Banks). But when she essentially proposes killing Lily and calls her Yoko because she broke them up, they decide that margaritas with Sal might not be such a great idea. Though Sal and Lily sort of reconcile in the end, they know it's time to hang up the shot glasses of their past and embrace the sippy cups of their future.
REASON 4: They like to surprise each other. Mitchell is the stickler of the show, without a doubt, but when he was invited to be part of a flash mob, he decided to use it as a surprise love letter to Cameron to prove that he isn't always so rigid. You really should watch the clip above.
REASON 5: They stand up for each other even when its risky.
At first, Cameron thought it would be too traumatic for his closed-minded, elderly grandmother to finally learn that he's gay and getting married to a man. But during a visit back to the family farm in Missouri, Cam eventually chooses his love for Mitchell over his fear of losing his family and comes out. "After the initial shock, Grams softened a bit," Cam says afterward. "She even agreed to attend the wedding." To which Mitchell corrects: "Standing outside with a sign."
REASON 6: They eventually listen to each other. Mitchell's plans for Cameron's Leap Day birthday are ruined thanks to unfortunate circumstances (a Wizard of Oz–themed party right when Cameron's family back home experiences a tornado). It leaves Mitchell scrambling to figure out what to do since it's a big one — Cameron's 40th birthday, though he keeps insisting it's his 10th birthday because he was born on Leap Day. The last-minute party on a yacht ends up being a complete disaster, but Mitch makes it up by honoring Cameron's wish to be 10 again. So the entire family skips the janky yacht and heads to a carnival.
REASON 7: Because their family loves and accepts them. Mitchell was legitimately worried about announcing to his family that he and Cameron had just adopted baby Lily, but even after the ridiculous theatrics of introducing her Lion King-style, everyone rallies around them. Even Jay, who is, deep down, a big old softie. Having the love and support of your extended family is definitely helpful when you're ready to settle down and start your own.
REASON 8: Cameron is still crazy jealous of Mitchell's ex-boyfriend, but for an unexpected reason.
For the first time, Cam meets Teddy, the only significant ex that Mitchell had, and discovers Teddy is good-looking and kind, and worst of all, Mitchell's family members are all still pals with him. We see that Cam isn't just in love with Mitchell, he loves being an irreplaceable part of a big family. Mitchell at first dismisses Cam's jealousy, which doesn't go well — "Congratulations, Mitchell. This is as sad as I've ever been in roller skates" — and then of course Cam rallies the family to show their true allegiances.
REASON 9: They make a good team.
When it was time to get Lily into preschool, Cam and Mitch teamed up against a lesbian couple to grab a coveted spot at an exclusive school. Then in another episode when one of their juice boxes stained a swanky neighbor's $50,000 rug, they rallied for a cover-up (blaming it on the woman's kid). Probably the best team-up was when Mitchell used his know-how as an environmental lawyer and Cam brought back his Cats costume and climbed a tree to stop developers from cutting it down. A favorite exchange from that moment:
Cameron: "Mitchell, where were we the first day Lily rolled over?"
Mitchell: "Under this tree."
Cameron: "Where is home base when we play hide-and-go-seek?"
Mitchell: "Under this tree."
Cameron: "Where did we take shelter during that dangerous lightning storm?"
Mitchell: "It wasn't a good idea, but under this tree."
REASON 10: They're willing to confront old issues, even when it's uncomfortable. Cameron confronts Mitchell's trouble kissing Cam in public. Eventually, Gloria realizes it's because Jay wasn't affectionate with Mitchell as a boy. That leads to Jay and Mitchell sharing a very awkward but well-intentioned display of affection, and then Mitch and Cam's own kiss. Does that mean that Mitchell is going to make out with Cam at the mall? Not necessarily. He's just not that kind of a guy. But maybe now he isn't as averse to the idea.
REASON 11: They are each other's support system.
Mitch and Cam thought for a while that they wanted another child, and at last they got word that a baby could be adopted if they rushed off to the hospital. But it all goes wrong, in an ode to Mexican soap opera melodrama, leaving our couple dejected. At first it's Cam who breaks down in disappointment at the hospital, needing Mitchell's comfort. Then roles reverse when Mitchell runs off into a field and Cam chases after him. Mitchell is tired of repeatedly getting his hopes up only to have them dashed. They lie on the ground, hold hands, and Mitchell can't help noticing, "I think I'm lying on a rock." Cam adds, "I'm lying next to my rock."