Lack of Desire in the Bedroom

I'm a first-year law student in a steady relationship, but lately there's been a stark absence. Last night, after hours of tender foreplay, my partner and I finally lay naked under the sheets. He entered me with gentle care, yet inside I felt nothing, no pleasure, no warmth, just emptiness as he moved back and forth. I watched his face contort in release while mine remained numb and detached. Is this normal? Am I broken?