Both dramas have a historical element (though LTM is a time-travel drama), and both feature love that should not be possible between the two lovers...

Both dramas feature love between humans and non-humans who had been living for centuries, waiting for their loved ones to re-appear.

Both are relatively light-hearted dramas featuring ghosts which eventually become friends with the protagonists. IASILY has a male ghost, N has a female ghost. Both dramas have a great balance of comedy, romance and melodrama.

Both dramas feature a romance with an immortal. My Amazing Boyfriend is more light-hearted with elements of action. Long for You is more reflective and slow-paced.

Both movies show stories of a male and a female teaming up to split up a couple.
However, the stage in life when that happens is different - the stakes are higher in "Honey Enemy", as the couple is about to get married in a few days time, whereas "Our Times" is about high school love.
Both worth a watch :)