I've always had a lot of fun pairing up characters, so I'm a bit bummed about that. Logically, though, I think limiting supports will make for better writing if executed well, so I understand why the choice was made.
Like some other people have said - I hope this means Byleths paired endings are less copypaste! The copypaste nature of the endings was really bad in Fates, IMO. Almost all of Selena's paired endings were "(husband) was well known for (thing) after the war. He and his wife, Selena, disappeared from public records after marrying". Since only Byleth is getting paired endings, hopefully they'll get some extra attention, and we won't get weird contradictions like that.