T-ARA JIYEON
They dated for 2 years, but they broke up after he came back to Korea after 5 months of touring around America and he found her in her bed with ZICO.
MONSTA X WONHO
They dated for 6 months, but they broke up after they fell out of love, now they're just friends with no feelings involved.
IU
They dated for 2 years, but they broke up after they fell out of love, but later on, they released that they were still very much in love with one another, but they stayed as a best friend because they don't want to ruin their friendship, again.