I don't really like how Eirika is a bride since the bride class doesn't allow swords to be used but I do enjoy using this class because overall it has pretty good stats and I like being OP while wearing a dress.
In my opinion:
MU x Gaius
Cordelia x Lon'qu
Chrom x Sumia
Ricken x Lissa
Kellam x Sully
Nowi x Gregor
Henry x Olivia
Tharja x Stahl
Theres probably more but these are the first ones that come to my mind :p
I finished Fire Emblem Awakening in Lunatic mode, I'm working on Lunatic + mode right now I wonder if this is alright~
I also finished playing Fire Emblem: New Mystery of The Emblem on Lunatic as well~