Has she called the ABA for advice and support for weaning? they may ahve some good suggestions for her.
At this age she doesn't need to replace the milk really, so it doesn't matter if he won't take it in a bottle. Does he eat well? Does he settle for daddy or others when she's not around? Can her partner take over bedtime/night-time settling for a while to give her a break?
It's hard to find a compromise when young ones are so attached to their mummies for comfort. Does she get much time out without her baby? A bit more quality time for herself might make all the difference in how she copes.