supposedly...
if you are healthy you are already happy and fulfilled by yourself, if someone comes along that is healthy too, you will be sharing the happiness you already have...
it is not that you are miserable and the other brings with him THE joy, THE good times, etc. etc... its more like both are building their own worlds and enjoy sharing...
love, respect, understanding etc are of course valid needs or expectations... but they dont arrive magically, the couple works on them every single day, words match actions....
those great mutual feelings you talk about come "naturally" though... no one is asking for them explicitly or demanding them from the other, or explaining how they look like or afraid the other will leave or obligated to be with the other person...
that world is starting to be known to me and ahhh its very relaxing, nothing like the rollercoaster i was used to lol
just my two cents.......