What that problem is makes a great deal of difference to how the romance is handled and resolved.
Thai dramas nearly always have some type of underlying problem or context. In fact, the inability of the underlying problem to fill multiple episode goes a long way to explaining why so many Thai dramas could be considerably shorter. (They average 12-20 episodes per season).
Until We Meet Again has a decent premise. It then meanders its way through what I call "shoe shopping" (characters go here; characters go there) before returning to its premise.
*Spoilers*
The premise is decent, and the handling of the premise is interesting and insightful. Over twenty years earlier, Korn and Intouch became lovers. When their fathers objected, Korn shot himself after which Intouch, who witnessed the event, also shot himself. At the funeral for both boys, the devastated fathers link their sons together with a red thread.
In other words, the plot's object is not to re-enact the past or to stop a re-enactment of the past. Although the characters return to the scene of their deaths, the possibility of a repeat is never a true fear. The object is to forgive and reconcile with past family members--and for Intouch (Pharm) to forgive Korn (Dean) for giving up so many years earlier.
Within this container, the romance (meeting, dating, consummation, proposal and future plans) takes place.
The container has a few issues. One is that I never fully accepted the connection to the past since the characters have such fundamentally different personalities. Pharm's previous self, Intouch, is sweet, extroverted, and happy-go-lucky; Pharm is reserved, pleasant, and tougher than steel. Dean's previous self, Korn, is pessimistic, withdrawn, uncertain, and impulsive. Dean is reserved and sometimes impulsive but far more self-confident and ambitious.
However, the premise--once accepted--is quite fascinating.Except--second issue--it simply isn't enough to fill 17 episodes. Consequently, the "container" carries the romance for about half the episodes; the college environment for the other half.
I have a similar reaction to most Thai dramas--so much so in the case of Love is in the Air, I began to wonder if all the studio's money got spent on the motorcycles, leaving the last few episodes, which have notably bad production values, to be carried entirely by the actors.
With Until We Meet Again, I wonder if the studio said, "Wow, what a great premise! It can be stretched--" only to find that no, it really, really couldn't. (Another supernatural/reunion series with the same actors--609 Bedtime Story, which I will address at a later date--does far better at 11 episodes.)
Of course, I tend to feel that most things could be cut. I maintain that with editing, Until We Meet Again would make a fantastic 8-episode series that would simply rollick along.
Hey, maybe somebody will do it!