People of Twins are more selfish and changable . They are only interested in new life and staffs even serious relationship. They always want to change their relateship. Maybe you are tired of your old life so you lost your interests and patients to your girlfriend.
If you want to keep your current girlfriend, make some shor term trip plan with her to change the environment. BTW, moving to anoterh area of Montreal will improve your relateship. Because you are twins , you love the changes in naything related to your life.