What is the obsession with gold-star wlws?

My ex-girlfriend and I recently broke up. She’s a masc lesbian and I’m pansexual. She was so weird when we broke up about how I’m “just gonna go back to dating men now.” I was so offended. It’s true that before her, I had only been in serious relationships with men, but I had only come out a few years before I started dating her, and it was while I was still in a relationship with a man, so I didn’t have much time for experimentation. But I’ve done things with other women, and my ex-gf and I were together for almost 4 years. How dare she insinuate that being with her was just like a phase or something? Who cares if I date a man, woman, or whoever after dating her? Why does she give so much of a fuck as to what genitalia or gender expression my next partner has? I’ve heard so many people relating to this as well, being bi and having a lesbian partner who is so weird about them potentially being with a man. My ex never showed any jealousy towards other women, but only towards men. Super biphobic and extremely weird. I understand that many lesbians are taken advantage of by bi women, who end up just having a “wlw phase” or whatever, so I get the initial wariness of getting into a relationship with a bi woman. But we were together for YEARS and I opened up to her so much about my sexuality, so how could she possibly still feel like I took advantage of her in that way? It feels so unfair. Any lesbians that feel the same way she does who can explain to me why they feel this way?