It's a dog, the next logical step is a dog
I'm a bit scared by the amount of people who are like "the next logical step is engagement".
They barely know how to communicate with each other. Carlos has yet to really figure out or understand the realities of being with an addict (or rather TK in particular - I'm not sure I'm hugely keen on these sweeping 'what it's like to be with an addict' statements). They just got back together after being broken up for months, during which it seems like they didn't speak at all.
I think we can give them a while to get a bit more settled before they think about marriage (or not marriage! That's also an option!)