2 weeks ago
She did it twice. You have to think about what she was doing and thinking. She knew she wanted to have sex that night, so she took a shower, got all prettied up, told you she loved you, went out with that attractive guy she'd been eyeing and flirting with for a while, they hung out together alone as usual, and they started touching and kissing. She thought about you for a second before she pushed you out of her head as she took off her clothes. Then they had sex, and were probably giggly and exploring new moves. Then when they were done, she put her clothes back on and called you at some point and told you she loved you. Then she texted that guy and made plans to do it again. She obviously enjoyed it and wanted more.
celly - 33yo - level 21 -
She had sex more than twice (guaranteed) and every time was premeditated, not an "oopsie." Plus, she might be thinking she'll only going to study abroad one time so she wants to experience everything as a once-in-a-lifetime opportunity, even if that means disregarding your relationship. It's better to ask forgiveness than ask for permission.
I don't know why she told you it happened once, and then she told you it happened *again.* There's no way she would have gotten caught, so maybe she told you because she wants you to end the relationship. It's easier to put it on the other person because that way they don't have to say "I cheated" and can have a somewhat delusional clear conscience about it and say "HE broke up with ME," which would be a twisted version the truth, but still saves them from looking bad.
You're young, I'm assuming she is too. One semester is NOT a long time to wait. If I were you, I would give her her independence back and take your dignity back. Don't be naive and reward her with your devotion and a place to live when she's done "studying." Can you even look at her the same? Can she look you in the eye as an honest, changed person? Hopefully this adds some perspective. Best of luck to you.