This is an update to this situation

https://www.reddit.com/r/asktrp/comments/6oy69m/update_break_up_with_gf_over_fantasy_problems/

Given the "advice" I was told here, that it's basically over anyway, I figured there was nothing to lose and in fact she might go and fuck him behind my back anyway or if we had a fight. If I'm there for a threesome she might get it out of her system and I'll have some control over it. Was also under the influence of basically the 24-hr hardon I have over this. I've agreed with her that we should do it and we spoke about it.

I accepted his invitation and we're all meeting for drinks tonight. He was just like "that's great," in an offhand way almost like he expected it. Should I feel insulted? Is there any way to assert myself during the threesome so that he doesn't steal the show, even if subtly so.

EDIT: no it's not a troll post. I added below a post to explain. Basically I'll have some control this way, she might fuck him anyway otherwise. I also know of a guy from the gym and his gf who did mmf with this guy and they didn't break up.