My former personal development coach calls what you are doing 'future worry' and it was my job to become aware when I was doing that based on nothing
except my own thoughts that I was imagining in my own mind; it wasn't based on actual current
Originally Posted by darkmoon
I know she will want <snip> she will want <snip> she will expect
I get that your expectations of how this person will behave in the future is based on your experiences of how she behaved in the past -- but, they are still only
expectations based on your assumptions:  that there has been no change; she has not undergone any personal growth or development, and,
 that she is still pining for the old relationship that existed between you in the past.
With any luck at all, neither of these will be the case and you will be able to enjoy the dinner in peace and privacy. If, however, this is not the case, then you can
stand up for yourself, or you can excuse yourself when she approaches you as has been suggested, or you can ask your host or someone else to run interference or
take care of your problem for you as has been suggested.