You are in correct in saying the heart is an instrument. However, the instrument is only used to facilitate the pumping and circulation of blood and nothing else. The heart, any heart has no feelings nor the ability to feel or help explain or verbalize emotions. The brain is also just a tool, an instrument to help humans be humans, however, all emotion is felt with the help of the mind. Feelings are felt and described in the mind. The brain is just a tool to aid in the facilitation of certain key bodily functions and also, to be considered a legally cognizant and "aware" human being. This does not mean the standard cannot change if the mind is discovered, it just means that for now, having a "normal" operating brain to aid us in the completion of daily normal task is considered legally cognizant. Both of you (GF and You) are wrong in indicating that heart is involved in any emotions. Emotions are involved in the mind and they are processed with the aid of the brain and certain key biological processes (i.e. release of hormones). It is a bit more complicated than this but rest assured that the heart and brain have nothing do to with emotions. You think you are in love with your GF, because you have the ability to think about the concept of love and about the concept of loving your girlfriend. When you combine these two conceptualizations, the end result that you think you can love your GF. If you cannot process the concept of love, then chances are you will not be able to think you are in love and if you can't think (think means to have the brain aid us in the daily completion of easy and daily task) then you might have a problem with your brain (brain helps you think, but You make yourself think). If you have a problem with the brain, then can be labeled legally "brain dead", but be 100% living through artificial means. Blood can be circulated, cleaned and pumped throughout the body without the heart. Give humanity a few more years and they will be able to do more. Heck, humanity might one day discover how to remove the mind and the soul from the brain and body and finally shatter the mind brain connection! In a nutshell, emotions are felt in the mind and do not necessarily have a lot to do with the body.