My girlfriend lost her father at the end of Mar.2011.. she bas slowly slipped into a deep depression.?

She is a nurse..and although she continues to go to work..she has all but shut me out..saying she is dealing with too much right now..I've been sending her flowers , gave her birhday gifts , given her cards expressing my undevoted love for her n basically letting her know I am here for her 24/7 . I still haven't gotten any response..I'm going to hang in there because she is. Wonderful person when she isn't depressed...help please