Kill the Spare
Still giggling at Inverarity's answer.
I really can't see Ron and Harry having an in depth conversation about women and hormones. For one thing Ron is going to feel really uncomfortable about thinking of his sister in that way.
If Ron is going to talk to anyone about being a father, then I think he'd be most likely to talk to his dad, or perhaps Bill.
But I don't think he'd go to them for advice - they'd probably be prodded by Hermione or Molly to encourage him to talk.
The way I see it, something cataclysmic would have to happen for Ron to open up about his feelings. If you take the Horcux stabbing moment as an example - Ron doesn't talk then at all. Of course it's obvious what's been going on in his mind, but if Harry hadn't witnessed the scene, Ron would not have told him about it.
Harry who finally realises how insecure Ron is (and he should have picked up about his insecurities long before) , and it is Harry who comes out with the 'She's like my sister' line. They may be great mates, but they're not at all intuitive.
Get Arthur to speak to him ... I think that's more likely.