Open relationship?

My girlfriend (trans mtf) asked if we could have an open relationship because she was curious about being with guys which I think is a good idea for her since obviously I can't satisfy that for her. However she also wants to open our relationship to other women and anyone else and I'm not sure how I feel about that. I don't want her to come to resent me if I say no but also I kind of feel like I'm not enough for her so she feels like she has to find what's missing somewhere else. She said at the end of the day we're each other's #1 priority and she said she wouldn't leave me and basically tried to reassure me that it's not about me not being enough, she would just like to try things she knows I wouldn't be into. I have no idea how to feel or how to decide does anyone have any good suggestions?