Should I have an affair? I'm in a loveless marriage and my wife suggested it.
That's strange. Why does your wife want you to have an affair?
She's jealous that I have many female friends with benefits.
It sounds like you and your wife need to consider a divorce. You both are clearly unhappy and it might be best for everyone if you break up.
It's not that bad, don't you think we work this out?
Letting another person in the marriage is never a good idea. It would just be better to end the marriage rather than to be with each other when you don't care about each other anymore.