I know what you mean.
I've read various interviews with Chris Gascoyne, and they are very ambiguous. From reading the spoilers, I get a strong impression he does love Carla.
I think the most brilliant thing about this storyline is the way it has been played out for over a year. Most affairs seem to happen fairly quickly, but I think a lot of credit is due to the writers for making us wait, and actually taking time with this whole storyline, IMO it has made it much more exciting, and meaningful.
After everything Carla has gone through, I think it would be cruel for Peter's actions to based with revenge. I reckon revenger could be a small part of it, but I think, and hope that the real reason he does it is because he does love Carla, and care for her, and want to be with her.
I see what you mean about her 'waiting' at the factory for him. I am certainly not condoning what they are doing, and I wish they would just get together, rather than have an affair, but like I said, I think the brilliance of this storyline is that it isn't Carla being evil and just wanting to ruin Leanne's marriage. At this point in time, she loves Peter, but I reckon she isn't playing for him any longer, she'd love him to be with her, but she isn't striving for it like she was all those months ago. I think there is a lot more to their relationship than most affair's which is why this is such a watchable storyline.
Sorry for the essay