Our two male cockatiels have paired up with us so that Maui is mine and Vinnie is Rachel's. That's not to say that they don't like us both; Vinnie will often come over to be with me (as he did just a moment ago), and Maui will gladly spend time with my wife, but Vinnine only likes to be preened by Rachel, for instance, and Maui prefers me. Here is Vinnie kissing at Rachel, showing he's hers... or that she's his.