Sex drive crashing

So I've been with my fiance for 2 years now, but the last few months my sex drive have seriously dropped like crazy.

I was already kinky to begin with so there isn't much different we can do to "spice things up".

It's like I'm horny during the day but by the time dinner is made, and kid is in bed I want nothing to do with it. Or even if I am horny and like mid way through I want to stop because I have zero interest and it doesn't feel good at all.

Any advice?