Additions, cuts and deviations

[Gertrude]

A noble maid's virginity is a highly prized thing that is used as a bartering chip for a good marriage for the family. I didn't get the impression that Robb was too worried about fathering a bastard on her, rather that he was highly aware that he 'ruined' her marriage prospects and did a huge disservice to her and her family. It was a flat-out insult to a family who showed him kindness. Sure, the possibility fathering a bastard on her is part of that thing, but it's not the whole thing. He's Ned Stark's son - doing the honorable thing has been hammered into his head since birth.

Of course it doesn't hurt that doing the honorable thing and the thing he wants to do coincide. He loves her so love and honor dovetail nicely for him. After the fact, he's going to either insult the Westerlings or the Freys so he's kind of screwed either way ... might was well take the way that he prefers.

I doubt he'd have the same reaction if it was a random chambermaid he'd been comforted by. She and her family are not valued, so no honor breached. Sad, but true in their world. Was Robb even a virgin at that point? I'd be surprised if he was and I don't remember it being addressed (granted, don't have them memorized)

This is not even taking into account the fact that Jeyne's mother has been actively trying to keep Jeyne from getting pregnant as per Tywin's wishes (we assume). I think having her pregnant and miscarry would be a greater deviation that just assuming he married her for the sole reason that he stole her virginity, virgin himself or not.

[Padraig]

I'd be surprised if he was and I don't remember it being addressed (granted, don't have them memorized)

I don't think it was particularly addressed. Hanging out with Theon wouldn't help but he did leave for the Iron Isles pretty early.