As a general rule, the difference should be noted in-universe as unusual. Generally, the man is the older one and the woman is the younger one, though it can be reversed as well. Naturally, this means that as the characters grow older, their age gap becomes less and less significant. As a general rule, when an older character is dating a character less than two-thirds of their age, it becomes notable for example, 9 and 14 is notable, 19 and 24 not so much 18 and 30 is notable, 38 and 50 again not so much. The age gap is often not significant because of the specific number of years, but because of the relative size of the disparity in age. Some characters can assume that the younger one is only in it for the money or nice gifts, or that the older one only wants to score a hot piece of ass and is not interested in anything else.
The age gap is often presented in the work as an obstacle that the couple must overcome as they might be judged by others. The age difference usually causes some raised eyebrows or disapproving comments from other characters in the story, like these: 'He's old enough to be your father!' - 'You could be his mother or much.
This is a romantic relationship where there is a big difference in age between two lovers.
