What was your breaking point?

Looking for some advice from ladies who are in at least their mid-20s who broke off a long-term relationship not due to cheating. My gf and I have been together almost 3 years and are struggling. We've grown to resent each other in some ways. But we still love each other. We also live together, have a dog, and are just so intertwined...I feel like our co-dependency has become a huge problem. I want to work on it and push through it, but I don't know if we're just wasting our time and are not compatible. Just curious what other ladies have gone through and why they choose to break up.