If she did, would she have cared?
LBJ was a bigger womanizer than JFK. There’s no doubt she knew about it, possibly even sanctioned it. Iirc there was a story that when Linda Bird dumped Chuck Robb for his womanizing (including with a Playboy Playmate) momma bird was quite displeased with her daughters action ...
Yes, but this (DKG) was in her own home.