I know it is a hackneyed answer, but talk. No one else's fantasies can be yours (although they might inspire fantasies of your own) - but find space where you can chat, and then discover what each other's desires are and try acting some of them out. Even if it doesn't rock your boat, maybe seeing your partner get excited by what you are doing will add that extra spark that you need, and give you the freedom to say what you want to try.
Even if you're in isolation with your spouse doesn't mean that you still can't be lonely. Dr. Karen Sherman joins to discuss how this is possible, what this means and how to address feeling lonely in marriage.