Feeling conflicted and longing to be with a woman... despite being in a relationship with my boyfriend.

I’ve been with my boyfriend for nearly three years, and I truly love him. We're both in eleventh grade, and he means the world to me. He often talks about wanting to marry me, and while I do love him and sometimes share those feelings, I can't shake this intense desire to kiss a girl. It all started with curiosity, but now it feels like an essential part of what I need to experience in my life. I'm so confused. I care about him deeply, but I know our relationship may not last forever—he hopes it will, but I’m aware of the statistics. My biggest fear is the thought of being with him for my entire life, which sounds terrible, I know. Maybe we’ll make it through high school together, and possibly even part of college, but I feel a strong urge to date a girl, and I can't emphasize that enough. Sometimes, this confusion and sense of regret consume my thoughts. I love him, I’m attracted to him—everything about our relationship feels real. Yet, I just can’t envision a long-term future with him.