Why did my girlfriend cry during sex?

My girlfriend of almost a year cried last night during sex. We haven’t had sex before and we were in LDR and never met up irl before because of the whole pandemic thing + uni. While we were doing missionary somewhere around the end of our session she shed a few tears while looking at my eyes. I asked if it hurt she said no... So what made her tear up? She wouldn’t tell me... :/ Did I do sth wrong?
Why did my girlfriend cry during sex?
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