i have the solution for you.
i have a friend who's like you.
he's single, yet he has problems screwing WGs.
he's horny and likes girls, but when he visits WGs, he gets nervous and can't maintain an erection.
(he has no problems with his ex-g/fs)
so i brought him to a KTV in China.
brought him to the parade.
he took 1 hour to choose.. (almost like choosing a wife)
when he finally chose a girl..
he spent 4 hrs in the KTV room, chatting and drinking.
(i instructed the WG to give him the best GFE)
that night he cummed twice.
next morning 1 more time.
he still felt gulity, but the GFE enabled him to maintain erection all the way.
after that, i went to KTV with him every week..
for almost 3 months.
now... he can do a 3-some anytime with anyone.