For your information, if others come across such insincere
girls, many would have forget about it and move on with their
lives. Either she is trying to give people the impression that she
*HAS* a boyfriend... OR trying to send mix signal to you - likely,
BOTH. Think about this, if she is staying at her boyfriend house,
its has nothing to do with you right? Even if she is staying at her
best friend's house, still nothing to do with you right? 
Let me teach you one unorthodox method to get the answer you want -
counter her moves. If she wants you to be confused - be firm and
sensible. When she msg you, oh, I staying over my bf house - reply
as the msg back as if you don't even give a damn. 'Alright baby,
enjoy yourself, but today sure too be happening one. Hehez.' kind
of msg. Remember this: Who are you to her right? And who is she to
you. 
Do not ever get xin ruan - soft-hearted, because if you do, you
never know whats her intention. If you know you sure won't be able
to make it through that way, commuication and settle once and for
all. Talk to her, make things clear. After you do that and before
you post it here to update the situation, give me a private message
saying that you communicated already: wait for my reply and see if
my prediction of that outcome is correct anot.
Cheers.
