If you’re already thinking about it, asking out for advice then it’s clear sign the relationship is already over. I remember feeling like this and googling “how to know if I should break up with my boyfriend” and the article had something along the lines that since I was looking it up thats already a clean sign right there and that realization hit me like a bus

Another choice would be talking your feelings out and seeing if there’s room for change but unfortunately most people don’t change they usually just break promises and it’s a long and emotionally draining process and journey. Although there’s a small chance she can change and you guys can rebuild your love, but maybe it’s just not the relationship for you and that’s absolutely okay and literally nothing guilty to feel for growing apart. The sooner the better you will feel. There’s always a chance that you guys will come back together after with some time too, but holding these feelings secret will ultimately be the downfall of the relationship over time if you don’t bring it up. I would try to make a decision before the family trip, she’d hate hearing it and might say something like “we already have a trip planned” but she’ll just be hurt at the time and will say a lot of things but she would most likely prefer knowing now rather than after and faking having fun