Honestly, I think Gwyn would be more than up for it, considering her incestuous daddy undertones. One less bitch hogging for his attention if they break up.
"Undertones"...right...
Girl flat out tells you (if you're a male lupine) that she wants you to RP being her father because she feels that you have so much in common with him (down to a roughly similar
smell) and she knows better than to actually proposition him, and said scene has her delving fully into those fantasies (including that she wants to bear his children and that she'll be a much better wife than her mother) and the Champ at times noting that coming out of the fantasy is going to be emotionally painful for her...never mind the fact that the first thing she does when her mother comes back is treat her like the homewrecking mistress of her errant beau. That's a fair bit more than just "undertones".
To your point though, I can
absolutely believe that Gwyn would openly (in front of everyone but Garth) ship her mother with the Champ in the hopes that it would drive a wedge between Gweyr and Garth. That said, I also agree with IraMorti that if she's been having pups with the Champ it might prompt some unexpected (to her) jealousy.
...Is it wrong that I kinda want to see Gweyr outmaneuver Gwyn on that front? Like, recognizing what Gwyn's trying to pull and playing along just enough to make Gwyn directly confront whatever feelings she has for the Champ and stake her own claim (so to speak) on someone she actually has a chance with rather than endlessly pining for someone that Gywn herself knows she'll never have?