Never feel guilty in not picking a particular cat, after all it is a life long commitment. Adopting older cats is just as rewarding, if not more so , then adopting kittens. You may still find a pair. Either ones that have been together or ones that don't even know each other. I have adopted 3 "pairs", two pairs never even met each other before coming home with me. Don't rush, you will know when it is right. It is actually a GOOG thing that most of the animals are spoken for. There will always be more (fortunately for you yet unfortunate for them....if you know what I mean)
Keep us posted.....I want to know when you decide!!!