The leads meet again in a work-related setting after years of separation. Childhood and young adulthood connection develops and the sparks are back.
Office relationship, where one of the leads falls for the other and realizes their feelings earlier, while the other seems to need more tome to realize or admit what they feel.
Both are office romances between a director and an employee. The Dorector Who Buy Me Dinner has a fantasy element to it though.
If you are drawn to the premise of red string of destiny and reincarnation, then Until We Meet Again and Tomorrow do have something in common, even though both are shows from different genres. Both shows are dealing with suicide, destiny and reincarnation, also showing flashes of past lives as memories or dreams, but have different approach to showing how suicide affects the connections with the loved one's in the next lives.