Does "lover" originally mean the person who you're having affair with?

[sula54]

I remember my English teacher said we have to be careful to use "lover" this word, because although there are many English words use "-er" as a person, "lover" doesn’t mean, "someone you love" but means, "someone you have affair with".
However, when I read the chapter of "Song of Songs" in NIV Bible, "Lover" and "Beloved" are showed everywhere and if we explain "lover" the word in dictionaries' way then the whole passage will be pretty interesting…

Does "lover" originally mean the person who you’re having affair with?

Best Regards,

Sula54

[Tdol]

According to the Oxford English dictionary, the earliest recorded uses were not the current meaning of having an affair, but love, feeling affection or the spiritual sense, all of which are to be found in texts from the 14th century. The first example of illicit affair given, interestingly, is from the 1611 edition of the Bible.