Why cant people believe I will love only him forever?

Does anyone thik it is possible to love someone forever. Jst one person wholeheartedly? I love only one person with my heart. My ENTIRE heart. everyone else i have seen i care about, but only cause i think i should. I want to love him alone. We are still friends, but he knows that i love him still. He tells me ill move on, but i dont want to. he tells me i dont need to change who i am, im perfect just the way i am.. he says he loves me but the way he used to. it hurts. i think he thinks i love him only because thats what i know. i think he feels that i idealize him but i dont. i just want him to be happy, and he tells me he cant be truely happy. i wish i could make him as happy as he was. I pray to God that he finds someone. I wish i was that one, but im not. I wont let him be alone anymore, and he knows how to reach me no matter where i am. He hasnt changed as much as he thinks lol in these 2 years, but he cares about me, and thats the only kind of burden i can be on him.is that ok?