Summary: My long-distance girlfriend recently hosted her ex-boyfriend for a few days, and they shared a bed. She insists that nothing occurred between them and that they are just friends, but I’m struggling to trust her. I could use some advice.

I (M26, living in Canada) was on a call with my girlfriend (F22, living in Germany) when I asked her about her time with a friend who had come to visit. That's when she revealed it was her ex-boyfriend, who lives in a different city where she attends college. She mentioned they just hung out and smoked a lot of weed together. She had previously told me they were still good friends and that their romantic relationship ended on good terms, with both realizing they were better off as platonic friends. When I inquired whether they shared a bed, she said yes, but clarified that she had two blankets and they didn't cuddle. She also mentioned she had informed him that she would be visiting me next month. My main concern stems from the fact that she cheated on her ex with me, and I have no idea how many other guys she may have been with. I only learned about the cheating when I visited her two months ago. She and I met last March while backpacking, and she stated that her relationship with her ex was on the rocks when she went traveling. She believes he might know she’s been with other people, but it hasn’t been openly discussed. She expressed that she doesn’t want to hurt him or lose him because she now views him as a brother. I've urged her to tell him the truth, and she says she plans to do so next time they speak. I’m not against my girlfriend having a friendship with her ex; I was friends with mine too (even though that never quite worked out), but I could never share a bed with an ex while in a relationship—that feels like betrayal. I'm aware of what typically happens in such situations, especially with alcohol and late-night conversations involved. Maybe my perspective is skewed because I've had romantic involvement with my ex, but being a guy, I can understand how men generally think. My girlfriend is stunning, and her ex has his appeal (she even posted about him on her Instagram story during his visit). While she might see their relationship as purely platonic, a guy’s intentions with his ex are often more complicated. As I write this, I can’t help but feel foolish; the signs seem glaringly obvious. Yet, I truly love her and she loves me. She justifies her actions by stating she wants to avoid repeating the mistakes she made in the past with her ex. She acknowledges my discomfort and says she would feel the same in my position. She apologized and promised not to sleep in the same bed with her ex again. I want to take her at her word but I struggle to do so, especially considering a few factors. Recently, we haven’t communicated as much—she had college exams and was feeling unwell, which I understand, but even afterward, our communication didn’t pick up. It seemed to improve only after her ex’s visit. She mentioned she tends to overthink sending me messages and ends up not doing so. I was already anxious about this situation before our conversation. When I saw her post about her friend on Instagram, I felt insecure but tried to rationalize that it couldn’t be her ex. Unfortunately, it was. There are numerous red flags here. Am I overreacting? How can I trust her? I often overthink everything, and my mind tends to spiral into worst-case scenarios. The facts are troubling: she shared a bed with her ex while knowing it would make me uncomfortable, she’s been distant lately, she didn’t clarify that it was her ex visiting, she cheated on him with me and possibly others, and she hasn't told him about her infidelity. Although we’ve known each other for a year, we only started dating exclusively two months ago after my last visit. Her relationship with her ex is significantly deeper and longer. She wants me to move to Germany when my visa expires in September, and we’ve made all sorts of loose plans to travel together. At one point, she felt like a dream, but now it seems like that dream is fading. Sorry for the lengthy message, but she’s coming to visit me next month, and I could really use advice on how to navigate this uncomfortable situation. Thank you.