Though they haven't walked the aisle yet, a source tells Star magazine that Britney Spears and Kevin Federline already "behave like they've been married forever." The source added, "They're very affectionate. You can see that when she walks she's in pain [due to her knee injury]. That's why Kevin is always helping her." Apparently that affection can pay off in other ways too. "They're at the bank a lot," a source revealed. "He's also at Western Union once every two days."