Moira was always supportive of Debbie and I think she had hoped that Cain would do the same with Holly but he pushed her to choose and he went in the huff when she refused to boot out Holly.
It's obvious she still loves him but she can't trust him which is why she keeps pushing him away. Sure he made a big declaration of love but the fact that he went back to Harriet less than 24 hours later kind of proves that she can't trust him. The last time she needed him he ran back to Charity, this time it's Harriet, the next time (if there is a next time) it will probably be Kerry. The whole thing is ridiculous but it fits in well with the rest of the current mess
It's Cain who doesn't deserve Moira IMO.