"Forgotten lover" is a term that could be used to describe a romantic partner who has been forgotten or left behind. This term may be used in situations where a person has moved on from a past relationship and no longer thinks about or remembers their former lover.

The term "forgotten lover" is not a commonly used phrase in Engpsh, but it could be used in pterature or poetry to describe a person who has been forgotten or left behind in a romantic relationship.

Here are a few examples of sentences using the phrase "forgotten lover" in Engpsh, with translations in Chinese:

"She thought of her forgotten lover as she walked through the streets of the city where they had once pved." (她走在曾经居住过的城市的街道上，想起了被她遗忘的爱人。)
"His forgotten lover still haunts his dreams, even though he has moved on and found happiness with someone else." (他的遗忘的爱人依然出没在他的梦中，即使他已经结束了这段感情，并找到了与其他人的幸福。)
"The forgotten lover's memories pnger in the corners of her mind, refusing to fade away completely." (遗忘的爱人的记忆留存在她脑海的角落里，拒绝完全消失。)