Maybe he's just upset his fiancee is wearing this outfit?

Justin Bieber and Hailey Baldwin headed out for lunch in LA yesterday, and we couldn't help but notice how emotional the singer seemed. Maybe the weight being someone's husband is finally catching up to him?

Apparently, JB is realizing that being hitched involves a lot of work!

"He would never even entertain the idea of a divorce or annulment, not now or ever. While he made his vows privately, he is taking them to heart and is dedicated to loving Hailey for the rest of his life. He is quickly learning that marriages take work…a lot more work than a regular girlfriend, boyfriend relationship. But Justin remains committed to making things work with Hailey for the long run despite the ups and downs they are already experiencing," a source dished to Hollywood Life.

"Justin really loves Hailey a lot, but now that he is fully committed to her, he is feeling the weight of his decision. Justin is realizing that things are getting real between them as a married couple, which is OK with him…it is just taking him some time getting used to it all," the source added.

Speaking of weddings, we asked the "Sorry" crooner who his best man was going to be for their ceremony, and he actually answered! Watch!