The Brief: To ship two people means to want them to be in a romantic relationship.

DEEP DIVE
The term ship is often used on Stan Twitter. It can be used to refer to people who are already in a relationship, who used to be in one, or who have never even met.
Ship can be a verb meaning boo’d up. As a noun, it is an abbreviation of relationship.
just unfortunately learned that one of Ariana Grande and Pete Davidson’s ship names is “grandson”
— Who? Weekly (@whoweekly) June 28, 2018