and I think that is perfectly normal.
Not all single woman are on the prowl for another womans husband, but they (we) are sometimes made to feel that way.
I do consider it takes 2 people to start an affair and one of them is the person we are / were married to.

Like all things we use our own judgement and err on the side of caution,especially if we are feeling vunerable, but do not demonize all single woman just because they are single and friends with a married man.