When you fall "in love" with your work, you become attached to it. You find yourself having trouble making even the simplest of decisions because everything is "too important" to let go of. You are likely to cling to a bad idea even if scrapping it and starting over would be easier. You begin to accept less than your best and it results in lazy work.
Once attached to your map you start treating it as an extension of yourself. In your mind, your map IS you and therefore when someone criticizes your map they are criticizing you. It is impossible to maintain this mindset and still be objective. This can cause you to be defensive of your map and hostile towards advice. Separate who you are from what you do. Loving your work or being passionate about what you do is very different from falling "in love" with your work.