I think I might have figured it out.
In Donkey Kong Arcade, Lady Pauline and Mario Jumpman were already married.
A few years later, at most, Cranky DK and DK Jr. kidnap Lady Pauline's daughter, Pauline Jr. and fight Mario Mario.
Thirteen years later, DK Jr. comes back from DK Isle after DKC 1, 2, 3, and DK64, and kidnaps Pauline Jr. and fights Mario Mario.
Thirteen more years later, after DKCR and DKCTF, DK Jr. is now middle-aged and works in the banandium mines, and saves Pauline III.