I have had a fantasy for a while about being cucked. About a year ago I shared it with my gf who was initially shocked but has since grown on the idea and we have done lots of role play with dildos and different scenarios. Last night we had some friends round for drinks and one of my friends ended up staying over. Once everyone had gone, me and my gf and my friend decided to have a few more drinks and we played truth or dare. Started off quite innocent doing stupid stuff and silly questions but ended up getting quite naughty. By the end of the night, my gf was fucking my friend while I was watching stroking my cock! It was amazing!!! I think this is the start of something great.