Oh yeah, age is just a number. Some people are old in age but young in mind, some are young in age but mature enough to handle life.
My husband is older than me for less than a year but I have godparents whose wife is 10years older than the husband but when you look at them and don't know about their age gap, they looks like they have the same age. Their relationship is okay but sadly our godfather died due to an accident.
Another godparents that the husband is more than 10 years older than his wife and his wife looks like his first daughter but their relationship is okay too.
You're right that age is just a number but love is what needed in the relationship.