DP and I had been together for 6 years when we decided to have kids (it had been something we'd talked about for years but the time hadn't been right before then), and don't really have any intention of getting married. Every now and again someone will ask if we're married or plan to become married, we say no, and that we don't have any plans to and it gets left at that. Never had an issue really, although my family have been prone to go into fits of excitement at the idea. It's more that they think it would be fun to organise a wedding rather than wanting to see us married. I'm not sure why they think that they'd be the ones organising it though.

My family are happy now that we have a child, they've got him to get all excited over so they don't care whether we get married now.

We saddled our poor DS with a hyphenated name. Both DP and I are only children so we both wanted him to have our surnames. He can change it to whatever he likes when he's old enough though.

In terms of justifying your relationship to others, best advice I can give is don't. If you are both happy not being married sod whatever anyone thinks.