I am much older than you but I do remember the feeling of being young and knowing I was growing up, and yet feeling uncomfortable with that, like I would be abandoning people who expected me to be a certain way or always stay the same person. But I knew I had to be ME!
When I was 19, I had a boyfriend whom I had been with since age 16. When we started dating, I was so happy and thought I hit the jackpot - he was so cool and cute and everything I wanted in a boyfriend. He was my first love and I was his. But by the time I was 19, about to turn 20, I knew I was a completely different person, and it wasn't working anymore. There was more heartache between us than joy and fun and lightness. He was intensely jealous, to the point that if I looked out the side window while in his car, he would ask me who I was looking at. Relationships shouldn't be full of angst. I felt like a free spirit who was trapped and held in a cage.
One day, I told him, "We're both growing up, but we're growing in different directions. You'll always be in my heart, but I have to be on my own." That is how I ended it. I knew it was time and I had to honor myself first. I never regretted it - he moved on, got a good job, eventually got married, started a business, had a bunch of kids. I didn't want that sort of life back then, and it would have hurt both of us if I'd have stayed and tried to give it to him.
Sometimes, the best, most loving thing we can do is to let someone go.