But, as it turns out, there's more reasoning behind the Wanderlust star's fashion sense than just coordinating with his bride-to-be.
In an editorial for Esquire, Theroux dished on his style, providing some insight into how he puts his outfits together—mainly opting for jeans and boots all year long.
So, why does he always go for that "winter from the waist down" look, even in the summer?
"Maybe it's my long-standing aversion to almost anything loose-fitting," Theroux quipped to the mag. "'Breezy' clothing, for lack of a better word, just seems so untethered, whereas jeans and boots have a grounding effect."
"In fairness to me, maybe my loyalty to these jeans and boots isn't so much an endorsement of them as it is an expression of my distaste for anything else," he continued. "Other options seem almost too grim to contemplate. Sweatpants? Cargo shorts? Light slacks?! Just the word slacks makes me anxious."
Although he doesn't mention Aniston in the article, we're thinking the motorcycle-riding aficionado has a little help from the thesp when he swaps his casual gear for suits (and when the couple is out on the town together).
The duo has been spotted rocking coordinating clothing on date nights around Hollywood for quite some time.
We can't wait to see what they sport at their wedding!