Is it true that talking about marriage can ruin a relationship?

[penguinZ]

My boyfriend and I have been going out for 8 months... We really love each other, and in fact he was the one that started talking about being together forever and talking about marriage and the future. I didn't feel uncomfortable about it because I really do think he is the right man to spend the rest of my life with. But were both young, were 18. And recently on the phone he told me that he is still shy, he's always been shy but he says he's still slightly shy. I told him what are you shy about? And he said maybe talking about future and stuff to give him time. I felt awkward and I don't know if I sounded demanding but I told him I didn't understand, and he told me to switch subjects but I couldn't. I was pretty mad because he was the one that started talking about all that not me. He could tell I was frustrated and we switched subjects but then all of a sudden we ended up talking about the day we would get married. I am confused. I don't understand if he's shy about talking about our future, or if he's just shy about openly talking to me or both. He's always the one that starts talking about the future so I just don't understand... I'm worried this can ruin our relationship. How do I get out of this mess? Next time he starts talking about the future should I tell him to realize he's the one that starts it? Or should I stay quiet? What should I do? Because I really do love him and I want to be with him forever I don't want this to ruin our relationship.