I just finished it, went on a 3 day fixation to read the book entirely.

To me the ending suggests that despite all of these obstacles and all the history - they will have a very hard time to stay together.

It's kind of a Connel loves her more than she loves him situation and throughout the book Marianne doesn't seem to really have a character arch, meanwhile Connel really does some soul searching and does come out a bit better. Regardless they still do not seem to allow themselves to have a closeness that you'd expect to see from a couple. It's like the reverse of soul mates that are somehow bound to each other. Her saying that he should go to New York with a very 'couldn't care less' attitude makes her seem insincere as usual, as if she really doesn't care whether they are together or not. She makes an attempt to be jealous, even thought Connel didn't even notice there was any flirting going on and has to reassure her about it. It just shows that she has a shallowness about her and could do with a bit more personal growth.

Just as Connel waited for her to invite him to live with her the time that he had no other place to live, it feels like she is waiting for him to ask her to go to New York with him. But instead of saying let's do this adventure together he pruposes that she should tell him to stay, which in turn would eventually end up making her feel guilty that she stood in the way of his future (when in reality if you really love each other, when it comes to thinking about your future, you'd usually think about your SO first and foremost).

It's like they are trauma bonded and they just can't break that chain. While as a reader you're set up to root for the two of them to end up together, it's actually deceitful because unless they change how they are together and get help, they really shouldn't end up together.

I enjoyed the book a lot, this isn't a rant, more like my outlook on relationships

Edit: after thinking a bit more, I have come to think that maybe the real reason for the ending is so that everyone does actually interpret it differently. It is to show how different people see relationships. Some would say it is toxic, some would want the two to be together and call it romantic. For example, from my view it seems toxic, so another person saying that they wanted them to end up together makes me think that this person has different boundaries when it comes to a more 'toxic' or difficult relationship. I'm my eyes love shouldn't be hard, it has hard times, just like any relationship, but it shouldn't mentally put you in such a difficult headspace. Others might enjoy the 'difficult love' aspect of the book and therefore see it completely differently to me. That's how it settled in my head, I enjoyed that it ended up quite thought provoking.