Well, I guess I'll quickly post my headcanons.
Chrom x Sumia
Robin x Lucina (Airship Canon convinced me in this one.)
Stahl x Sully
Vaike x Miriel
Ricken x Maribelle
Gregor x Nowi
Virion x Cherche
Libra x Tharja
Gaius x Olivia ("You're a worse liar than your mother." was mentioned to Inigo in B support. Gaius knows that Olivia is a truly terrible liar, which is shown in B support. Pie also means canon.)
and not so much which is
Frederick x Cordelia
I don't know what Panne's would be.