Loneliness in Our Marriage

I'm a stay-at-home parent to our two-year-old. My relationship with my partner is good in every way, financial stability, mutual support, affection, but lately I've been feeling a disconnect sexually. It started subtly, him preferring cuddling over sex more often, but now it's rare for us to be intimate at all. Last night, when he was sleeping, I woke up craving him, wanting what we used to have. In the dark of our bedroom, alone with my thoughts and my body, I felt a deep loneliness that made me ache inside. It's not his fault; I know this. But the absence is hard to bear.