My girlfriend blocks me from viewing her status sometimes on WhatsApp

I just discovered that my girlfriend of three years with the mindset of getting married had been blocking me from viewing her WhatsApp statuses, i was at my friends and he mentioned a post my gf made on WhatsApp on monday.. I couldn't remember seeing that post so i assumed I probably didn't check statuses during that period that was why, while my i was playing game, he saw something funny on her status and showed me, i hadn't seen it yet so i went to check through my phone . But i was shocked when i didn't see her posts on my status. I felt embarrassed and betrayed sort of. I wonder why she'd do that, i wonder what type of things she usually post that she doesn't want me to see. I never imagined she'd do that and i feel really hurt as a result.. why do you think she blocked me? Is it a healthy habit in a relatioship for that to happen? What should i do? Please advise