I think the lack of other characters was deliberate.
It was Claire who was there for Catherine and Ryan after Becky's death. The photo albums and Ryan got that message through. Catherine has always seen it that she propped up Claire in her recovery but she didn't give credit to the amount Claire did for her.
The two grannies, the physical holding her up, the crochet blanket all showed us that.
Similarly the very violent TLR reminded us of what he is. We feel sorry for his shit life but ultimately his view of the world (and the forgiveness comment) is totally skewed. His feelings for Ryan are genuine but he doesn't really understand love. Ryan provides a window to more normal feelings but he's too damaged.
And I don't think it was the end of the policing career that meant Catherine lost the haunted look but the realisation Ryan is not TLR. It was a big contrast to the end of series two as she looks at him running on that hill..
Loved it!