You may want to rethink allowing your cats outside. The average life span of indoor cats is about 14 years – though this is reduced to 4 years in cats that are allowed to roam free. By allowing your cat to roam outside, you're risking them getting run over by cars, or attacked by other animals. I don't know what the coyote situation is near you, but I know many people that have lost their cats to coyotes near where I live.
Cats do fine indoors by themselves (although it's always preferable to get them a companion, if the cat gets along with other cats). Just make sure you have things to keep him interested -- I got a fish a couple of months ago, and my cat adores watching it all day :)
To answer your question, though -- I'd wait a couple more weeks. She may still come back.