I don't know how old your baby is, but it's only recently me and my partner have started being intimate again (6 months postpartum) and the frequency has SIGNIFICANTLY decreased. Prior to this I was breastfeeding, and the main carer for our little boy, and I'd end the days being completely "touched out" and would feel the exact same if my partner tried to initiate anything, even a kiss. Could this be a possibility?
Your probably feeling touched out.