My gf and I have a third girl that we sleep with. I have no problem having sex with my gf when having a threesome, but I can’t keep my erection for the other girl. I do have to wear a condom if I have sex with the other girl - but the second I even reach for the condom box, my erection is gone. And once it’s gone, it’s gone. I feel like I’m letting the girls down and confused because this is what I want and feel lucky to be having threesomes. I feel like I’m wasting a great opportunity got really fun bedroom play. If anyone else has been this position I’d love some tips.
My thoughts immediately went to having the two women laying side by side and you dipping in and out of both of them, to try and keep yourself where you need to be before going full-bore on the other girl? 
Having a similar issue though with One person -
You can “Love” but at the same time your penis can have a mortal fear / aversion to going in there and forcing him … is hilarious.
As In he’s So determined like a horse he de facto escapes a cock ring …
I’m working on it . 
Yeah I had that exact scenario - but I have to wear a condom specifically for the other girl, my gf does not want me to have sex with her in the same condom. So it’s when I take the time to put it on that I lose it. So annoying