Something like Epiphanies of Rebirth where the characters are not immediately smitten to each other. The goals of the characters are not love related and they work their ass off to achieve their goals.
Slow romance Completed novel Clear and Muddy Loss of Love, Female General And Eldest Princess, My Wandering Spirit Lady The Witch Nichang
Check my reading list. There are only few BLs here but has relatively slow romance. The only novel with fast romance was a 6-chapter story so it's fine. I guess?
Hmm...does My Husband Has a Terminal Illness count? Chapter 80 something and they're finally about to start an actual relationship
Completed Earth is Online I’m Not Shouldering This Blame Seizing Dreams Reborn As The Villain President's Lover Heaven Official’s Blessing The Founder of Diabolism Very Happy Spring Trees and Sunset Clouds Spirit Hotel Ongoing Don’t Pick Up Boyfriends From the Trash Bin Fantasy Farm