Gambit made a fatal flaw by not proposes to her, they went through a lot in the series and rogue indirectly said she was ready for a marriage...she told him, she wanted a lifetime quoth him and yet he turned her down Even bishop asked her about how come she did not have a ring on her finger.
It was a missed opportunity from gambit's part.
However it may have been a good thing in the long run...most marvel marriages ends in disaster but it will have be nice to see gambit and rogue take that next step seeing how they are such a fan favorite pairing.