I'm not putting a mathematical formula on love, I'm putting a mathematical formula on what I'd consider "normal" age gaps. Saying "20 years" or "5 years" is just silly, because age differences get less and less important the older you get. The age difference between a 60 and a 70 year old is a lot less than the age difference between 20 and 30. Or lol, 10 and 20.
To be honest though, I don't really care how big the age gap is, as long as they're both past the age of consent.