Scroll far enough into TikTok's marriage discourse and two terms begin to blur into one: the lavender marriage and the mixed-orientation marriage. They get used as synonyms. They are not, and the difference is worth getting right, because one describes a life organised around concealment and the other describes a marriage with nothing to hide.
A lavender marriage is a marriage of convenience designed to disguise the sexual orientation of one or both partners from the outside world. A mixed-orientation marriage is broader and plainer: a union between two people of different orientations, entered into openly. Every lavender marriage is, in effect, a mixed-orientation one. The reverse does not follow.