It sounds like he is really sort of emotionally available and commitment phobic. He can behave in the way people do in relationships, loving, attentive, etc… but his beliefs aren’t going to allow him to accept a long-term relationship, and something will have to change those beliefs before he will see himself with anyone long-term.  This really is something he should mention to people up front, especially if he knows the person he’s dating is looking for something long-term.

He seems to be blaming his parents’ relationship on marriage itself, as if they wouldn’t be fighting just the same without it, which is misguided, but he has to figure that out for himself. I also know some people don’t believe in life-long relationships because they think everyone gets sick of each other eventually so they want to leave themselves free to break up whenever they’re sick of the person (even if it’s 8 years later) rather than commit to marriage…. which is fine if they believe that way, but they really need to make sure the person they’re dating has the same belief and is NOT looking to eventually marry.

I agree with your friends that it’s better you found out now. The belief he has is a strong one, and it’s not likely to change by dating longer. He would’ve just found more and more things to nitpick you over (looking for basically any excuse to end things once he felt your relationship was getting a little too long-term for him) and eventually would’ve broken up with you the same way, but your feelings would’ve been deeper and it would’ve hurt you much, much more. The one for you will have the same beliefs about marriage that you do.