As I wrote previously, I've done both and in the end, there is more intensity for me in not being there. I'd love to watch her seduce a man with me there. Like a dinner guest with whom she'd flirt with increasing boldness, then sit next to him on the couch as we watch TV or have after dinner drinks, touching his leg or arm until he takes the hint and then fondling his cock, and letting him run his hand up her skirt to find her pantiless pussy waiting for his finger. Then unbuckling his pants and taking it out while I dim the lights and encourage them both by taking mine out to jack while they continue on. That's pure fantasy though, and 99.9% will always remain so. The only way it might happen is if she had a lover for a while, and he revealed that he was into it and wanted her to. It would have to originate with him, and that's unlikely.
Having said that, the hottest of all scenarios, for me, was watching my ex-wife when neither of them knew I was watching. I went to get a pizza, having agreed with her that she'd try to seduce him while I was gone. I drove half a block and then returned to watch them through a window. It was so hot watching her tease him with touches, standing next to his chair on the pretense of showing him a photo album, her hand stroking the back of his neck and her big tits almost literally shoved into his face. He put an arm around her, and then dropped it to fondle her ass, at which point she lifted her top up and her tits WERE literally shoved in his face and hands. His back was to me, so I couldn't see everything, but I could tell when her hands moved to the front of his pants, and could see the movements of him unbuckling his pants for her. She dropped to her knees and sucked his dick until he came in her mouth.
Then I raced to go get the pizza. When I returned, she whispered to me that she had sucked his cock, and I acted like I didn't know it. After the pizza and beers, she began flirting him openly in front of me, and we ended up both fucking her good. To this day, neither of them knows that I was watching. For me, that's the best of both worlds. Being there and not being there at the same time!
