What do you call secret love in Japanese?

Answer 1

If by secret love you mean a person, you might try "kakushi" (concealed man). If you mean the love itself there is "mitsuu" (literally secret relations i.e. adultery) or if its secret to the other person maybe "okabore = unrequited, illicit love.) Sounds like you have some interesting homework.

Answer 2

The most commonly used term is 'Koibito' when referring to a boyfriend/girlfriend.

Wives or Girlfriends also commonly use anata when addressing their lover, the english equivalent of "dear" or "honey"

It is also common to for a someone to call his/her partner by their first name with no added honorary endings.

For example, let's say someone has a girlfriend named Jane Smith

Smith-san would be an honorary title which is usually used by the general population to address someone that they are not very close to or are an acquaintance of.

Jane, standing alone without any honorary titles, would indicate that the person saying her name is very close friends or possibly lovers.

Answer 3

sore wa ai dayo