It sounds to me like she just can't quite get past a monogamous way of thinking that tells her not to cross a certain boundary with a man who is YOUR husband. It doesn't sound like she doesn't want him; it sounds like she's afraid to have him, perhaps because it's "wrong" to her or she feels it would disrespect you somehow. So she focuses on others to take her mind off him.
But something else struck me about what you wrote:
Originally Posted by dreamyer
Several years ago I came into my own as a bisexual woman. My husband has been very supportive. I've been free to have my own experiences. He's been free to join whenever my girl was willing.
So it sounds like you can do what you want and he participates if the woman "is willing," as you said (I have a personal dislike for calling women girls, sorry). You said it's been fun. Well, now, sometimes she's willing and other times not willing, so what's the issue here? Why should he pursue it? Why should she change? Did he stop letting it be a casual, from a "if it happens it happens" kind of thing to something where now he's expecting sex with her? Maybe she's feeling pressured in some way.
Sounds like hubs should get his own
girlfriend(s) and leave you to yours.