The thing I've found with little mo too is that she was more than happy to be with Alfie in front of Billy and even ask him to keep it secret for her, but as soon as he finds happiness with someone, she then decides that she does care for him afterall. It wasn't so long back that she had decided she loved Alfie. I feel for her in one way, but the majority of me thinks that she needs to let Billy get on with things.