a relationship with an expiration date?

so i'm seeing The Boy still, and it's getting to be more serious. i guess it could be considered a real relationship now. which is exciting. i'm really starting to dig him. but i'm talking to my friend last night and he said, probably joking, that i should just end the relationship now because he'll never marry me. and i was shocked, and kind of hurt, but said, well you know it's been like a month, i really don't think we're there yet. but i know it's true, and i think that's why i was hurt. i mean it wasn't something that hadn't crossed my mind, not the marriage thing, but do i want to get into a relationship that i know doesn't have long term potential? i mean, don't get me wrong. it's not like i have to know the end game or anything. but do i want to invest the time if i am just going to get my heart broken?
i mean The Boy, by talking about the past and his other relationships, has given me an insight into what our relationship will be like. not bad, just that i will never meet his family, his parents. i joked about it last night, saying, of course your parents will love me! everybody's parents love me! and he just smiles. and so a little more seriously i ask what it is that they wouldn't like... which basically turns out to be because i'm a blond haired, blue-eyed, catholic. no big deal. great. no big deal.