Hye Jung is definitely more pitiful of the 3. Mi Ho is irritating, granted, but she's young and immature. Hye Jung is a grown woman, with a good career and a kid.. she needs to grow up and stop throwing tantrums.
Tae Sung is actually being quite mature about it i think. he keeps trying but knows he's 2nd best in Ha Na's mind so he's pretty understanding really when she always ends up back with Joon