It does look like the two of them have already communicated somehow in the past...apparently, it can be possible that this 'other' person just don't have the 'time' to speak/communicate with you or doesn't want to go through the 'trouble' of doing so. (the signing, writing, etc.) There are indeed folks like that and it's just a sad thing that some folks will resort to that type of behavior or attitude.
Anyhow...in the meantime, just keep 'smiling' at her (no matter what kind of facial expression she'll present at the time)..one thing I have discovered that has helped tremendously for those kind of folks who pretty much ignore people like 'us' (the deaf/hoh/c.i.)...is this: There will be a time when they might need help or struggling with a certain task, going up to offer a hand (to help) or just pitch right in and help--does break that seemingly neverending cycle of whatchamacallit type of attitude(s) the 'other' person is showing and oftentimes, things change right there, gets better from then on. Indeed, it can work wonders, but not always...however, it's worth a try! 
Hopefully something good will come out of this eventually..just hang in there!! 
~RR
