Wife
In typical language, a wife is any slut exceptionally important to You. She is presumed to be always either near You, worn by You, or soul armoring You. Importantly You alone decide who gets to be a wife, and how many sluts get to qualify as a wife—whether one or hundreds. (As a general guideline if the list is too long to practically read, it may defeat the point of categorizing wives separately than other sluts.) Unlike with other status conditions, Your whims and beliefs are the only factor determining whether or not a slut is a wife.
Presumably each wife is consummated with a special sacred ritual specific to Your preferences, which is known in prophecy as a Marriage Rite. In pop culture any slut believed to be one of Your wives is symbolically depicted wearing a Bridal Band and Wedding Dress, but how often these are actually worn depends on Your preferences. Once a slut attains the legendary status of wife it is presumed to be permanent, but You can of course change which sluts are Your wives merely by thinking about it.
The status condition of wife immediately ascends a slut to have a tier no less than the one You're currently interacting with primarily. If You're in consensual combat with immortals, Your wives will ascend to at least immortal-tier; if You are fucking goddesses, Your wives will ascend to at least goddess-tier, and so on. Aside from this being a wife imposes benefits tied more to prestige and privilege than a change in stats or ability. Because You like wives so much, wives are presumed to be chosen first for enviable roles that interact with You, such as being a vessicle slutskull or bitch-blade.