Our last night together in Me

You drove two hours just to come pick me up and take me back to your house, as you had done many times before. We were being silly in your car, blasting music, singing at the top of our lungs (I’ve never done that with anyone by the way) and suddenly you stopped, so I looked over at you and you just smiled. I stuck my tongue out and started singing again, and so did you.
In that moment I thought Us would stick, I truly believed I’d found someone who could actually make me happy.
That evening we went out, you took me somewhere new, one of your favourite places. We got back to your house, went to bed, made love, fell asleep holding each other as always.
The next morning I went to pick up my car from the mechanic, we had breakfast together and then you came to my car and kissed me goodbye, there were no signs of hesitation. We texted as usual that day but the following morning you decided you didn’t want a relationship anymore. I was heartbroken, I am heartbroken.
The worst thing in the world is not understanding something and I just can’t wrap my head around what you did, it’s killing me.