Dating equivalent of 'spouse'

Solution 1:

Ordan & Wintner in their study¹ on representing natural gender have observed that there seems to be no neutral hypernym for the pair boyfriend/girlfriend.

MF This class includes nouns which have distinct masculine and feminine forms, but no gender neutral one.
Examples:
boyfriend/girlfriend, lord/lady, male/female, prince/princess, uncle/aunt.
17 nouns are in this class.

¹ Src: (pdf: 86kB) ^{Noam Ordan and Shuly Wintner, Representing natural gender in multilingual lexical databases, Dept Comp Sc, Univ of Haifa, p3., p7.}

Solution 2:

There is squeeze in slang. Though, it is used as a sexual partner too. I don't know if there is much difference nowadays.

There is also main squeeze but it has somewhat a stronger sense than squeeze and you can call your spouse as your main squeeze too.

Main squeeze "most important person" is attested from 1896; meaning "one's sweetheart, lover" is attested by 1980. [Etymonline]

There is lover and sweetheart but they are usually used for someone more intimate and more suitable to use in longer relationships.

There is date but it is usually used for a companion of a single occasion.

Let's go with valentine.