There's actually an interesting twist to this. In Awakening, each child-bearing character has a single character that they can gain support with easier than with anyone else (support growth). The pairings are-
Chrom and Sumia (Lovebirds)
Lissa and Vaike (Best friend's sister)
Frederick and Maribelle (dote on royalty)
Virion and Cherche (from Valm)
Kellam and Sully ("tough" Shepherds)
Stahl and Miriel (leftover Shepherds?)
Ricken and Panne (Ricken loves animals)
Gaius and Tharja (both are a bit shady)
Libra and Cordelia (Uh...)
Gregor and Nowi (he saved her)
Henry and Olivia (the last two adults you get)
... Oh, I misspoke... the kids also have "canon" pairings!
Owain and Kjelle (strong fighters?)
Inigo and Cynthia (flighty and flirty?)
Brady and Severa (YES)(also, snark and bark)
Gerome and Nah (dragons FTW)
Yarne and Noire (Uh... v.2)
Lucina and Laurent (the mature ones)
Everyone else is forever alone (Lon'qu and Donnel most notably).
You can see more about it here-
http://serenesforest.net/awakening/characters/supports/support-growth/