If I’m understanding the movie chronology right, the guy who is a peer of her father figure actually married the teenager from X-men, in the comics? I thought the first Wolverine movie took place in Logan’s past, which means Gambit is problematically older than Rogue, no? Or is Deadpool not the only thing that movie got wrong?

Keep in mind the comics chronology and movie chronology are completely different (and the latter of which is rendered basically unuseable by the decision to have movies skip a decade between each one). 

In the comics, Rogue was not a teenager when she joined the X-Men; but rather around 22-27. Indeed, by the time she joined the X-Men, she’d had a pretty substantial career as a supervillain as part of the Brotherhood of Evil Mutants, she’d stolen Ms. Marvel’s powers and almost killed her, she’d attacked the Avengers Mansions and gone toe-to-toe with the Avengers before having to retreat, she’d broken Destiny out of Ryker’s Island, she had a bitter rivalry with Dazzler, she’d fought the X-Men and Rom the Spaceknight, etc. 

Gambit is around 25-28.