Patrick is currently single. But on Facebook Evonne and Elizabeth made a statement on their statuses about how Patrick DOES like UK singer Jody Williams. Jody Williams is a singer who won the South African version of "American Idol" a few years back.
We know little about Patrick before the age of 16. At that age he was captured by Irish pirates and hauled off to Ireland where he spent his remaining adolescent years as a slave. He finally escaped at the age of 22.
No, in the series, it is not stated that Sandy likes Patrick. It is more common to think that Sandy and SpongeBob like each other. Sandy actually shows that she thinks that Patrick is an idiot, so I personally do not think she would like him then.