Dear FGB readers: I need your help with my girlfriend...

From a male FGB reader

I've been in a relationship with my gf for about 4mths now & apart from d normal bf/gf squabbles, it's been all good. I occasionally pick her from work though she drives as well. I've been into her office on 2 occasions though. She closes at 5pm but often comes back at about 7pm & says she's working late. So, when she called me after 5pm & said she was still in d office, I decided to drive by her office at about 8pm on my way from work so we could stop by a sit out b4 getting home. Her car wasn't at d office & she wasn't picking my calls. She'd left d office & I drove to her house but she arrived an hr later saying she'd work errands to run.
All d while, she didn't answer my calls saying she forgot her phone in d car. When I told her I was by her office earlier, she got so infuriated. She called me a stalker. So I wanna ask fellow LIB readers, is it possible to be a stalker in ur gfs life? And when I told her to change her 'not picking calls' habit, she told me point blank that she'd not change & what was I gonna do. She's on d stubborn side but such defiance? So fellow LIB readers, what do I do?