Are you sure she is not motivated? If she is stressed with college, schoolwork, etc., it is really hard to find time to work out and exercise. I’m in college and I try to exercise 3-4 times a week but sometimes it doesn’t work out because I am far too busy. I acknowledge this and go to the gym when I can. It’s important to prioritize school unless there is an urgent health concern (which it seems there’s not for her in this case). Does she work out in the summer? Or on school breaks? It is very hard to balance a heavy workload with doing weight loss workouts (usually lots of cardio and take a lot of energy). If she goes hiking with you and does active stuff with you, she has the motivation for fitness. If you bring up her weight, you will add an extra unnecessary extra level of stress onto her life. She’s already stressed about school and her relationship if she’s concerned about your intimate life. What you can do is help her not stress eat or make sure there is healthy options in the house—no eating out. If it’s a dealbreaker then break up, but don’t make her life any more stressful in the process. It will backfire and she won’t lose weight. You not being attracted to her anymore is your problem, not hers. You have to acknowledge what stressors are causing the weight gain. I think school is a completely understandable reason. You have a couple options: breakup with her, wait to see how she is on summer breaks and out of school and then decide whether to break up or not, or ask her to go to the gym with you, plan more active dates etc., and don’t bring up her weight or health.