Doona made it very clear since the start that she would end things if Haesol wanted anything more than a sexual relationship and Haesol agreed. Once he confessed, Doona refused to meet him again, moved out and refused to give her address to him. Despite this Haesol continued to be persistant and pursue her anyway, despite knowing she doesn't feel the same way.
Haesol is old enough to make his own decisions. He made his own bed and now he needs to lie in it. I feel bad that his love is unrequited but I don't blame Doona in the slightest, it's not her fault at all, she didn't lead him on in a single way and made her intentions clear from the get go.
In the very beginning he never agreed to a relationship without feeling. And I mean from the moment he put on her underwear
I seriously don't like how Doona treated Haesol... I mean, it could be seen that he had a crush on you, but you still decided to let your lust win over good sense. Then you just decide to dump him because of those feelings he had since the beginning, and she knew it...
... I don't know, she is really sexy and all, but her choices as a person totally suck for me. That's the only downside I feel when reading this (￣∇￣")