Without getting too overly theological, what needs to be addressed is the motivation of people at given ages. At 14, your motivation is probably friendship and it is true that females mature faster. The average female at that age is already thinking of their future wedding and their wedding dress while the guys at that age are just starting to get sexual fantasies and desires on their mind - two different mindsets.
Eventually your mindset will shift towards college and future careers and eventually marriage and a potential family. There are numerous mindsets we shift into as people grow up, to say you like something now does not mean you will down the road. I know in my life, I nearly lost my Catholic faith and nearly did things I would of deeply regretted because I thought the girl I liked (as a 16YO) was my “perfect match”. I thank God things did not work out because looking back on it I sacrificed my faith for pleasure, and it really showed how immature I was.
All sustainable relationships should be built around Christ. A marriage is 3 people, Christ being the center. By growing closer to Christ we ultimately grow closer to each other relationally (check out Theology of the Body as you get older). My advice to you is to continue to be friends with this person but focus on growing in your faith and getting closer to Christ, that is what matters at this stage in your life