I finally told my wife about my fantasy [cuckold]

I finally told my wife that my only sexual fantasy is the idea of her being fucked by other men. Not with me watching, just knowing that it's happening or has happened.

Her reaction was pretty neutral. She asked why and I tried to articulate it, then she said "interesting" and went to sleep.

I have no idea what this reaction means or how to progress from here. We've been married 25 years and I can't believe she can be remotely satisfied with our sex life. I hear so many stories from guys who encouraged their wives to fuck other men and found that they became more energized, happier, more confident… that's what I'd like to see.

As I say, I don't need to see this happening. That's explicitly not the point. I want to know about it afterwards, and there would have to be a couple of rules around not ruining our existing social life, but apart from that it just comes down to making her understand that I'm completely serious if she's remotely interested in doing it.