I don't know if there is a maximum number of weeks; but, having a vampire sim (she's a young adult with 85 days to adulthood), I have found that since she is 5 star and knows EVERYONE in town, when she is invited to parties no one is there when she arrives or they are just leaving (though they invited her). When she goes to hotspots for dancing (party sim), people who are arriving immediately leave (as well as the mixologist and bouncer). It's almost like no one can stand to be in the same room with her!