I was in that exact situation. Let me tell you what to avoid:
It was 2002. I had just recently turned 19, and graduated from high school back then. I was madly infatuated with this gal that was 15, and about to turn 16. I knew there were some bad kids trying to be a bad influence on her, but I wanted to be a part of her life, and be a counter to it. However, she was torn. She appreciated my willingness to pour out all manner of devotion and affection on her, and that I believed she was so worthy of my time. But... she wasn't entirely sure she was ready for it yet. And she was also confused by all the bad kids tempting her. She didn't know how to react to all these different pressures in her life.
Then, her mom made the choice for both of us. She said: "You are about to enter college. She is still in high school. That's creepy. Dump her. NOW!"
I felt it was completely unfair. But I complied. I let the girl know the reasons were her mom's, and that I loved her no matter what. She said she totally understood, and wished me well as the two of us parted ways.
That day, I could barely hold the tears back. It was as if she died. And I never forgot her, or my feelings for her.
With me out of the picture, the bad kids had no one left to stop them from turning her against her mom. The family fell apart, and she turned to crime out of despair. They got her 9 months in juvie for robbery. Then, they got her hooked on drugs. From there, the drugs took over her life. And killed her for real in 2013. Like a sick joke too. I was reconnecting with her, and she was about to start a new job. Then she overdosed on heroin. I called out to her, and she was too weak to resist.
I wanted to attend her funeral, to pay my last respects. Her mom made sure that nobody saw the body. My symbol for her and me was two navy blue dolphins against a teal sky and a navy blue ocean. I drew it on a balloon, and launched it in the air near the river - along with everyone else that the family considered "undesirables."
They buried her faster than the feds tried to shut down investigation into the death of Anton Scalia. She was the black sheep. But they can't take her memory from me!
Be very wary, that your prospect is not in this situation. Spare yourself from my haunts. Don't choose a girl that will in the end, leave you with only what Good Charlotte said best: a ghost of her.