Hot water bottle

This is an analogy that I've been thinking about lately. It's not written about anyone - I just like hot water bottles.

Our relationship was like someone holding a hot water bottle. At the start, you were so warm, and I would hold you, taking in your heat. Though the rest of the world was cold, you kept me snug, and I held you tightly, selfishly.
Over time though, things changed. I still felt the need for you, but you'd cooled. What I felt as a warm touch from you was merely heat that my own body had given. I tried to keep us both warm, but the cold inside you was too great.