It could go the other way. Doris not liking Catherine and that drives them apart.

I'm basing this on the clips we've seen, but Doris comes off 1 of 2 ways for me: no one is good enough for her son, thus how she acts with Danny in the car or she really wants Catherine and Steve together because Catherine can totally hold her own and Steve needs someone like that in his life and blah blah blah.