Two Cairns in a Home

Question
We recently (two months ago) adopted an abused Cairn Terrier.  She (Molly) is a quiet, sweet, and loving dog of 6 years old.  We also have a Cairn (Gus) who is 4 and been with us since he was 12 weeks old.  He is a lively, active, loving, and friendly to everyone except Molly.  He ignores her for the most part, but if she approaches him, he growls at her and then walks away.  I believe he would love to see her disappear for good!  
In my human eyes, I had envisioned these two happily playing together, sleeping together, being good friends, but it is not moving in that direction.  I do not see Gus as an alpha dog.  Molly would seem to me to be the more likely alpha. They walk well together and no problem with eating (she gobbles her food, but does not approach him while he lingers over his).  She wants so to be friends, but he just won't give in to playing with her, letting her sit next to him, or sharing anything together.  He simply ignores or walks away from her - treats her with disdain  Any suggestions?  Is there a possibility of them never becoming friends?

Answer
Just continue to ignore this behavior and I am sure Gus will eventually come around to some degree. The fact that he is tolerating her is a good sign.

You seem to think that Molly is the more dominant dog, but I do wonder from your description of Gus's attitude toward her if maybe *he* isn't the more dominant dog (in his mind, anyway, which IS what counts). "He simply ignores or walks away from her - treats her with disdain." These are the actions of a dominant dog who sees no need to reinforce his dominance with a lesser dog. Just because we want something won't make it so.

Bless you for giving a rescue a forever home!