I hate to sound cold, but, deal with it. Live for yourself, and do whatever makes you happy. Grandparents aren't going to be around forever, so, you shouldn't take their deaths too hard, they've obviously lived long lives and are somewhat prepared to leave everything behind. As for your girlfriend, I assume you are ~12-17 years old, and at that point in life, relationships are not that serious. It'd help to know what shes bitching at you about :P, but regardless, just apologize for whatever you may or may not have done, because that's how it works with women.
im starting to hate my life, everyone expects me to be so great and my dad is always yelling at me..my gf is bitching at me right now and my gramma just died..fuck v.v