Why would a guy ghost me after 2 months of dating?

We met on a dating site. Clicked right away, and he payed me a visit twice, within 2 months. (We live in different countries) Asked me to be his girlfriend, and we already had plans for next month. Then, after the last visit which was on Saturday, he only sent me a text saying he has some kind of problem and isn’t feeling very well. I’ve asked for an explanation, called him once but no answer. Is it over?
Why would a guy ghost me after 2 months of dating?
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