There is a lesbian couple in The Promise Of The Soul (Taiwanese drama) that recently ended. Though they don't have a huge role but it is more than what you see with the couple in Secret Lover. They are a mature/adult working couple that own a bar. There are scenes of them in several episodes being lovey dovey.
https://kisskh.at/780954-the-promise-of-the-soul

AthenaTheStorierX:
I'm gonna go back on on my phone to get screenshots, but y'all we won. We had a GL second couple in the Taiwanese BL drama "Secret Lover."
They're very DL (Down Low), but their proximity throughout the drama had my radar going haywire. And indeed, in that last episode they confirmed that they've been kissing off-screen a lot. Will we be seeing a bit of a surge of Taiwanese GL after this tester?
And is this the first Taiwanese BL drama with a GL side couple? I can't recall another one - but I am very behind on my dramas.