You 2 known each other for over what over 1 1/2 years now. I don't think she would just leave without leaving a note, unless she is that type of person.
I don'y know. I try not to act apon assumptions (its ok to make them though, just not act apon them).
Usually, when my gf gets mad AT me, it takes me a little while to figure out whats going on. I try to look at the situation from different angles. Luckily I am usually right (but when i get it wrong. migth as well give me a shovel). My gf usually just balls me in with the other problems of her day(or weeks, or months). So I understand and she understands how thick headed I am and takes me a little time to understand the situation. We don't even really argue, or at least I don't. I know I could never win. But later on I poke jabs at she only if its funny (to her).