Well, this is exactly the same that happened to us when we went on holiday in the summer. Harvey, at this time, was 7½ months old and would quite happily let all of us handle him (me, my husband and two teenagers).
He went to my parents' house for the holidays, where they let him out each day etc and on our return Harvey decided that it was just me he would favour. He wouldn't let my husband, or the kids, go near him.
Anyway, fast forward from July - it's not good news, things are about the same. He'll happily fly to my husband and "hang out" with him, but if he tries to stroke him, or touch him in any way he shows aggression. My husband is now getting to the point where he feels he's tried all he can (I think he feels a little rejected) and isn't too bothered about handling Harvey.
I don't know the answer - we are persevering, it's not working. I hope my husband doesn't give up though.
Anyhow, you are not alone - there's loads in the same boat - I think you just have to give Cybil some space and try gradually to regain her trust. Good Luck xx