Hahahahaha. Sorry, I'm not laughing at you, I actually hope to be laughing with you. ;)
Yes, it's a big dilemma.
While watching Secret Garden - my fav. drama, by the by - I loved Oska because he was downright hilarious, not because I cared about his love life. On the other hand, Tae Son is an extremely endearing character and I understand why you want him to be happy - supposedly with Oska.
I obviously can't make you change opinion on the matter, but I think dear Tae Seon is MUCH better off without Oska, than with him. Although funny, witty and very warm hearted, Oska is an egocentric, who can only be together with someone with a strong, independent personality, not a young guy who still has to discover the world.
In conclusion: I believe you should keep on watching SG and, perhaps, try to see the funny side of Tae Seon&Oska's "courtship", instead of fantasizing about a romance which, as you already know, will never be. :)