I feel like an idiot, is my girl gay?

I've always been a confident guy. I'm tall, good looking, masculine, got a built body big and I think I'm pretty smart/funny.Never felt insecure next to any other guy. I'm also pretty open minded and ually liberated/experienced I guess. My girl and I do swinging, and at the clubs girls drool over me and beg us for . I don't have a problem with my girl doing another guy cuz I'm pretty sure that I'm better than him. I do it mostly for myself since I get to enjoy other gals. Here is my problem though. Few weeks ago my girl told me that at the swingers clubs that she's attracted to the girls sometimes and would like to try something with them. But she doesn't wanna do anything in front of me & likes to be alone with her. Me being the fool that I'm say K you can have any girl you want for your BD. Couple of days after her bd she comes home with a foxy chick, kinda punk rock.I sleep in the next room & all night I hear my girl moan/screaming from s. More than ever with me.