Another culprit can be the medications used to prevent and abort migraines. Some of these drugs can really do a number on your mood. It's pretty hard to remain your normal cheerful self when you've got all this other junk going on. Truth be told, it IS hard to deal with side effects. Sure, it might help your headaches some, but it's just hard to carry on normally when you don't feel at all like yourself.
Weight gain can cause image problems, lowered self-esteem and feelings of hopelessness.
Tiredness can cause problems with work and relationships, which in turn put additional strain on you and increase stress. Nausea and other stomach troubles can make it awfully difficult to eat right and function normally. And then there's auras. Many people have problems with confusion and forgetfulness before, during, or after a migraine episode. This also can cause problems with work, family life and your social life.