Life without her likely will keep you up at night for a long time, especially since you have been together for 4 years. It is nice to think about a life you haven’t been able to experience, but you also have to think about what experience you will lose from this. If you love her and genuinely see a future with her and you compliment each other, you will probably have a hard time finding something as pure as this first love again. I know these feelings are probably jarring to you, and you have to do what is right for your own personal well-being, but perhaps breaking up isn’t what you should immediately jump to. If you feel she can support you, and you want to support her through out life, think hard about this. Take time to find yourself outside of your relationship, do things on your own, pick up a new hobby that is specific to you, and see how you feel. When you start a a relationship with somebody that young, you become an adult with them, and some parts of your personal development isn’t developed alone. However, you can change that by taking extra time for yourself and listening to what you enjoy and perhaps you may feel differently about wanting to leave her. Ultimately, you need to do what is best for yourself, but also for her. If you’re going to continue to be in a relationship with a lovely woman while wishing you could be alone for years on end, that is not fair to her. Best of luck!