At what stage of you relationship did your wife admit she wanted to be shared?

She very much wanted me. They approached me at my job where he hinted that she wants me. I didn't think much of it but she was giving me the fuck me eyes constantly, although she was definitely less open about it than him
 
I'm pretty attractive so I didn't really need to. I flirted with her and told her I'd love to come over, and I did. According to him she's usually a lot more reserved than that. he was there but wasn't in the room