Wanted to rec Happiness but I saw you’ve already watched it. The other title which came to mind is Sell Your Haunted House, but there’s no romance between them.
dramas/movies with power couple who get together early and fight against a common enemy
Love O2O* - "Enemy" is probably too strong a word generally, but they are united when they take on personal and business problems.
The leads take a while to really get together properly, but they are a strong team (they are both skilled at fighting, warfare, strategy, political maneuvering or similar) with real power couple vibes and they take down a common enemy:
The leads take a while to really get together properly, but they "fight" well together (in a gaming context) or work well together to beat a common rival / enemy / villain:
Love O2O* - "Enemy" is probably too strong a word generally, but they are united when they take on personal and business problems.
The leads take a while to really get together properly, but they are a strong team (they are both skilled at fighting, warfare, strategy, political maneuvering or similar) with real power couple vibes and they take down a common enemy:
The leads take a while to really get together properly, but they "fight" well together (in a gaming context) or work well together to beat a common rival / enemy / villain: