Let's clear something up. All breakup excuses are legit. And let me tell you why. If a dude decides to breakup with you for some bogus reason, consider yourself lucky that he did you the solid of removing you from his life before he brought you into a non-sensical web of ridiculousness and lunacy. Game. Set. Match.
Regarding this particular chap. My guess is that he's just waiting for the right woman to come along. A lot of people say they're done and don't want to get married, etc. And maybe that's how he really feels. But maybe he just hasn't met the woman to change his life yet and make him realize those are things he wants to share with her.
I know what and why you're asking. You're trying to figure out if it was you or him. And chances are it was both. He didn't want to be with you that much anymore and decided to bail and let you know that he was just done altogether. He just wasn't that into you. But also, maybe he felt like he was doing you a favor given how he felt at the time about no kids or marriage.
So the truth is that, based on his current actions - I guess, a year really isn't that long - you can feel better about yourself and just assume it was all about him. But realize that when he starts dating again - and he will - it has nothing to do with you. You just weren't the girl for him at the time. It happens.
All breakup excuses are indeed legit. Even if the person lies to you about why they want to break up. The bottom line is they want out. And if they lie about the reason, it's probably because they want to spare your feelings or don't want to fess up to something they did to ruin the relationship.