fun4three
All people are different. We are together 20+y and we are the best friends first and great lovers to each other ofcourse.
When it becomes clear that we need for spicing up our sexlife somebodys help, we tried it. Ofcourse it took time to get from fantasies to real, but we did right.
Now what comes to the psychological engagement then ofcourse you got to be a bit in love to make love 
But same time you share it with your best friend you have definitely stronger bonds… With the friend who is happy for your pleasure, luck and other good things. Your friend who will always stay there, wait you home and share your good and bad days.
We like cuckolding more than other combinations and involvements as its just easier and more comfortable for me (husband) and she likes it as well.
Do not expect her to go out to seek a guy for sex as she have sex enough with you as guantity. She will do it with pleasure only if the flirt and the mood are real and chemistry appears between her and stranger. And she has to gain trust in both sides – she must feel secure with the other guy and she got to be sure that you support her whatever happens
We have had (unfortunately) small number of partners, but all the experiences were great as they came up naturally from real life.