"What if Asmodeus and Raei are divorced lovers?" No. What if they're twins? Fucked up Vex/Vax parallel.
If you really want to ship Asmodeus with one of the gods, may I present to you the funniest possible option: Avandra the Changebringer.
"They hate each other, tho." Yeah, and? Rivals to lovers to enemies is my favorite trope. It's juicy. It's messy. It's bloody. Right up Asmo's alley, tbh.
My one (1) piece of evidence for this: In the Calamity, Asmodeus stole Avandra's necklace, the Kiss of the Changebringer right from her neck and locked it away in of the Betrayers' temples.
My guy, why are you stealing kisses from your archnemesis? Are you like in love with her or something?