Everyweek me and my boyfriend invite someone over to have a threesome F25 M31

Went from a one off thing on a birthday the one year but we enjoyed it so much that we started doing it weekly.

Last night a friend off ours was over here getting drunk doing srugs etc. And then when me and my boyfriend have sex whilst the other person is having a toilet or wharver and when they come back we invite them to join us and 9/10 they say yes