Feel free to answer without reading further, this is my situation:
My current relationship is both online and long-distance (before it's asked, I confirmed she is not a catfish). Eight months. I'm American, she's a Syrian medical student in Turkey. We met on Facebook. We started somewhat like pen-pals, and it steadily grew from there.
We used to Skype for hours at a time. She would stay up late to talk to me; I adjusted my work schedule to make it easier for her. She's been under enormous pressure at school these last few months (she'd be up at 3 or 4AM multiple nights per week), and we stepped it down in deference to that, to the point where we were only texting intermittently. I had been researching residency programs at US schools she could apply to but hadn't shared my findings yet.
We last IM'd three weeks ago. It was cordial, but she stopped answering in the middle of the conversation. It was another late night, and I figured she went to bed. Two days after that, she deactivated her Facebook account. There has been no contact since. I've tried reaching her via Skype IM (which she rarely checks) and her email (which gets flooded). No answers.
I pride myself as a patient man. I understand shutting down Facebook; it's a distraction, she did it (briefly) when we were first acquainted. Had she told me what she was going to do and why she needed to do it, I'd have been willing to wait however long it took until she could reestablish contact. She didn't say a word.
I want her to be happy, and I thought she could be happy with me. I wouldn't resent her decision if she wanted to end things, but I would hope she'd have the courage to say so.