So we have had experiences with MMF, my wife has to like the person and feel some connection.  We have a fantasy "friend" and we both agree should it turn real he would be treated as a second husband and with all the benefits.  I do shift work so when I am work they would do everything a husband and wife would do and obviously going to bed and fucking.  I used to be a very jealous person but since I have experienced watching her being fucked by another it now turns me on no end.  The idea that we have another cock on tap to see to her needs is a big turn on.