Justin Bieber's video with 'Mrs. Bieber' may be the sweetest thing we've seen in our lifetime.

We're still awww-ing like cheek-pinching grandmas after seeing the photo of Justin Bieber and his little brother Jaxton on the red carpet MuchMusic Awards red carpet. But now we can't stop swooning over a video Justin shared of him smooching Mrs. Bieber! (WARNING: Justin's Believe album release and "Justin Bieber Live" and/or these Swaggest Justin Bieber GIFs may already be causing dizzying feelings, but your heart will melt into a pile of goop after watching this clip.)

Watch Justin Bieber's "Me & Mrs. Bieber video" after the jump!

Before you freak thinking that your invite to Justin's and Selena Gomez's wedding got lost in the mail, "Mrs. Bieber" is actually a nickname Justin gave one of his littlest fans, Avalanna Routh. Avalanna is a 6-year-old girl who suffers from a rare brain cancer. Justin met her when he visited a children's hospital in February. The "couple" formed an instant bond, and they "got married" in a special ceremony. They even talk on FaceTime, and Avalanna attended Justin Bieber's "Today" show performance and made a special cameo when Justin Bieber sat down with Matt Lauer.

But the real heartwarmer is the short video Justin tweeted of himself kissing Avalannah on the cheek before performing at the Apollo. The clip catches the pair chatting and snuggling like total BFFs. Justin's compassion and care for this little fan is obvious and abundant in both the Viddy and the "Today" show interview, and we're absolutely blinking back tears as we write this. We're loving how Avalanna doesn't want to let go of Justin's embrace, and we don't blame her. This is "One Less Lonely Girl" we don't mind Justin spending some up-close-and-personal QT with. Side note: Maybe we should introduce her to Selena Gomez's would-be husbands!?