mostly it happens when your case is kept in delay, my medical was expired their first priority to process the cases which in the initial assessment are selected for interview waiver, if they call you for interview they might have some concerns about relationship and other things, my advise will be send as much papers as much you can for proving your relationship delay in case is not good sign but sometimes it happens due to backlog of the application if too many applications come its hard for them to process on time and cases are being delayed so dont worry...!
