Nae sarangeun saeppalgan rose
Nalkaroun gasiro neol apeuge halgeol
"My love is like a red rose,(simile)
it may seem beautiful now,
but my sharp thorns will hurt you"
The singer is trying to say that her love has it's side effects, it can be very hurtful. Although it is beautiful like a rose, towards the end of the relationship, her love is painful like a thorn.