It’s been said that Song Ji Hyo used to date fellow actor and co-star of GOONG - Joon Ji Hoo. There were tons of rumours about the pairing (they were rumoured to be co-habiting together as well because Ji Hyo frequents his place every so often.)
Ji Hoo has also been quoted saying Eun Hye (his other GOONG co-star) isn’t his type, speculating netizens’ suspicions that Ji Hyo was rrly his type (and also his gf.) Ji Hyo has been quoted saying "Ji Hoo is good for dating"
In RM episode 24, Ji Hyo once confessed that she’s dated an actor before (but did not reveal the name when probbed.)
Since Ji Hoo’s controversial drug abuse news broke out, I’m not sure if Ji Hyo is still dating Ji Hoo though.
But currently, I feel that she’s dating her fellow RM colleague, Kang Gary. *detractors GTFO*
Me and a fellow Monday Couple-shipper has compiled some theories about the little hints that shows how Ji Hyo might actually be involved with Kang Gary irl. You can go through my old entries to read it up. (I’m too lazy to backtrack the whole goddamn entries lol)
seriously. me and a fellow Monday Couple-shipper decided to set up tinhatmondaycouple to post all our crayzee tinhat theories abt the Monday Couple’s real life romance (but we’ve yet to officially post stuff in there yet.)
SO STAY TUNE (and get yourself a tumblr account like, srsly. lol) ^^v
[Disclaimer: Answer may be correct or vice- versa. It’s just theories (“my opinion”) from all the hints I’ve gathered.]