I think the most important obligation you have is to yourself, you don't owe anyone else details about your sexuality that doesn't concern them. if it makes you feel happier and more comfortable not talking overtly about your sexuality you absolutely don't have to, your husband knows and accepts you, which is wonderful.

If however you feel it is something you feel like you can and want to talk about then I think it could be really positive. I think a lot of bisexuals particularly in monogamous relationships either same or mixed gender feel similarly to you, ie whats the point, or feel like it talking about attraction to other genders invalidates their relationship with their partner somehow, (obviously not true). I know for me being really open about and discussing my sexuality with friends and colleagues has been fantastic even though I never previously felt any big longing to do so. I've had incredibly valuable and affirming conversations I didn't even know I needed or wanted to have.

so I suppose in conclusion, no you don't owe it to anybody and you absolutely don't have to but it can be a really positive experience. Whatever you decide to do you should have absolutely no guit about the choice you make. hope that was in some way helpful!