There are several reasons why a person will "feel bad". One major reason is this:
Everything in your life is your creation and is a part of you. When you create something in your life, YOU have expanded, and your creation is an expression and extension of YOU. It is a part of you. This applies to EVERYTHING in your life.
If you buy a car, the car is a part of you. It contains your energy. If you have a friend, that friend is your creation and a part of you. If you own a home, TV, cell phone or piece of jewelry, all those things are an extension and expression of YOU.
Just as your body is an extension of the SELF, and the SELF is an extension and expression of "God" (Universal Intelligence; Universal Consciousness), everything in your life is an extension and expression of the SELF (the real you).
Your spouse, your kids, your boss, your job, your watch, your house, your "title", are all expressions and extensions of YOU. It is all the "expanded" YOU.
If you cut off your toe, you would feel "bad", because you just lost a "piece of yourself". In the same way, anytime you lose anything in your life, or anything in your life changes (like losing a job or lover), most people feel bad as well, because they lost a "part of themselves".
Even when people "lose" weight, they often "feel off", because they lost a part of themselves.
This is seen very clearly with people known as "hoarders". They can't throw anything away. They have to keep and hold on to everything. If you take the most meaningless item (a small box of old bottle caps) and tell them you are going to throw it away, they will get upset, agitated, anxious, or even cry.
This actually happened on the TV show "Hoarders". The guy started crying when they were going to throw away a very small box of about 12 odd useless bottle caps. Keep in mind, this man had over 6 very large barns full to the ceiling with "junk". He did not even know what was in the barns, all he knew was that "he HAD to keep everything".
With this knowledge and new data, anytime you feel bad, ask yourself, "What I am losing". When you discover this, you may have a cognition, and release the "attachment" to the thing that is not permanent anyway and you will feel better.
When you have the realization that everything is temporary, and that all things "change", you will realize you cannot "lose" anything.
Do this, and you will never be the same.
Much love and compassion to you.