Whatever it is, we are not likely to guess unless you provide some context. A singer and a title would help a lot.
PS: Welcome to the Forum :hi:, panpaen!
But there is no reason to suppose that marriage is implied. ;-)
Not in the keys part, but marriage is indeed mentioned in "buy you the finger things". To me, that means first the engagement, then the wedding ring.
In Mexican Spanish no distinction is drawn between girlfriend and fiancee. The word novia serves for both. I think that implies something cultural: in Mexican culture any relationship between young people of opposite sexes is presumed to be somehow related to potential marriage. No such cultural presumption exists in contemporary AmE. We can even contemplate "friends with benefits", q.v.
Urban Dictionary: friends with benefits