TL;DR: I'm a lesbian and my gf secretly went on Tinder for a few months matching with guys because she wanted the euphoria of feeling like a "normal woman" that men are attracted to. What do I do???
The situation:
My (22 F) girlfriend (21 MTF) of almost 3 years admitted to me recently that she was using Tinder to talk to guys. For context, she came out at 19 in college before we started getting close/dating, and I am her first serious relationship since starting transitioning. As she started to feel more comfortable and confident in herself, she became more aware of the fact she was bisexual and not a lesbian.
Admittedly, as a lesbian who went through a previous breakup with a woman who had used me as an experiment and realized she didn't romantically like women, I became worried and wasn't as supportive as I would have liked. Also, as someone who is masculine-presenting and considers myself agender, it triggered feelings of insecurity and low self-esteem about my body and my identity as someone who isn't and doesn't want to be a man. I'm a bit shorter and smaller than her and I don't have a very masculine frame, so aside from the way I dress/express myself, I can't be "her man," or at least not in the steretoypical 'big, tall, physically dominant' way.
Within the past year, aside from other tensions in our relationship as 2 young adults juggling college and work, something that's been bothering her a lot is this notion of "being wanted by a man = being secure in the societal position of being a woman". As much as there's logical understanding that this is just patriarchy talking, it's something that has been at the front of her mind as she continues to pass milestones in her transition. So, being with me, a butch lesbian, meant that she couldn't experience firsthand real attention from men, and also came with this notion of being societally "othered," which has caused her distress at times too (she's stealth and wants to be as "normal" as possible so as to not be questioned/clocked or put in danger).
So, torn between not wanting to lose our relationship and desperately wanting to know what it felt like to be desired by a man, she started using Tinder this past fall until around the end of January, matching with guys. She told me that she didn't ever meet up with any of them and usually didn't have any conversations except for brief exchanges on the app, mainly to reveal she was trans and gauge their reactions. She did this as an experiment to prove to herself that she was indeed a pretty woman that men could like/want (even though I've been telling her that for ages).
She broke the news to me recently because she wanted to wait for a time that was more "neutral" so I could digest the info and make any choices before big life events that are coming up (I'm graduating college & deciding on my future living/work situation & whether we'll live/be together after grad). She told me she's heartbroken about the choice she made but that it was ultimately extremely helpful/educational in terms of alleviating the stress of wondering. She has apologized a lot and told me I can react/say/do whatever I need. She said she knows it's something that warrants breaking up and will understand if I decide we should, but that she really hopes we can still be together. She said the experience only made her more certain that she loves me, wants me (finds me attractive/desirable), and wants to be with me.
She is starting therapy soon as she finally feels like she's in a stable enough position to do so, financially and mentally/emotionally, and says she wants to talk more about her strong/obsessive need to always chase things that will "prove" that she's a "real woman" (in her words, "why it always feels like a moving goalpost"). I understand that she's going through a lot, and I really want to support her in feeling safe and more at peace to just be herself, but I'm not a life coach or neutral party. I'm her partner, and what she did was a huge breach of trust and betrayal.
We've been talking about it for the past few days, and there's definitely so much love between us, but I just don't know how to move on from this. I'm really torn because as much as I want to be with her and continue our life together, I don't know if this is something I can accept and forgive or not, even knowing that it came from a more nuanced place than pure infidelity...I understand we both need therapy for all this, but I wanted to put this here to get others' input who have similar identities or even similar situations.