Sister wife Robyn Brown turns green with envy Sunday, but it’s not for the reason many people would think.

“Sister Wives”: The name alone is enough to get people to tune in, but once people find out it’s about three women who share the same husband, the show practically sells itself. OK, so the next part appears obvious, too: They all have to be envious of each other, right? After all, some girlfriends fight over the same shoes, let alone the same man.

Most of the time on the hit TLC show, however, the women seem to be living in perfect harmony, but on Sunday night’s episode the ladies of “Sister Wives” fly into a jealous rage. Well, one of them does, at least, and it’s not exactly over who is the husband’s favorite.

Robyn has been tense wondering whether her new home will be ready before Christmas, but in the latest episode of the reality-television show she is thrilled to find out her house will in fact be ready for the holiday. Awesome, right? Not exactly.

Her excitement is short-lived when she finds out sister wife Christine Brown’s house will also be ready by Christmas. Because husband Kody Brown is only one person, he can’t see both houses at the same time, so since he is already with Christine, he goes to see her new abode first.

Let the drama begin. At the end of the “Sister Wives” preview, Christine is shown saying that at one point she wasn’t being a good sister wife, and it’s something she needs to work on.  She loves her big family, and she indicates that this is the type of lifestyle that makes her the happiest.

Behind the other women’s eyes, however, it seems like something is missing. It’s hard for a monogamous person watching the show to understand how a woman would feel fulfilled by sharing her husband with three other women.

“Sister Wives” is shown on TLC Sundays, with the new episode this weekend beginning at 9 p.m. EDT. Check out the preview below: