Discussing opening up; partner says she is fine with me seeing others, but she's not interested in seeing other people. Should I not go ahead?

I (late 20s, non binary) have been in a 5+ year closed/monogamous relationship with my girlfriend (in her 30s). We lived together for the first few years but are now in a long distance relationship due to our careers. I spend 2-3 months out of the year with her and plan to continue doing so until we are able to move back in together. We have not had any other relationships as adults (I dated as a teen), and I am the only person she has been with romantically or sexually.

From the very beginning I had asked her how she'd feel if I hypothetically felt like I wanted to have sex with other people, and she had always said that she would be okay with it as long as I discussed it with her. She said that she understood that she may not meet all of my needs because she has a specific situation wrt sex. She cannot or will not do most things I enjoy (vanilla or kinky) and she has a low libido, all of which I respect; we have sex only a handful of times a year. She also said she she was not interested in seeing other people for two reasons: she feels fulfilled by her relationship with me (emotionally, sexually), and because she feels that no one would be interested in her at all. When she states this, she doesn't seem emotionally invested other than some mild frustration because she thinks I am wrong to think there are people who would be interested in her.

I have been seriously talking to her for 6+ months about opening our relationship. In addition to feeling sexually unfulfilled, I have had gender confirmation procedures while we've been together, and would like to explore my sexuality with my updated body. Every single time I try to have this discussion she just restates what I detailed above, and that she will just deal with any emotions that come up. At most, she says that she is scared that I might leave her if I meet someone else. She has not sought out information about ENM, does not talk to her friends who are ENM/poly about our discussions, and did not talk to her therapist about the situation until last week on my insistence.

In December, I asked for permission to initiate a FWB relationship with a close (but long distance) relationship-anarchistic friend, explicitly saying that I felt I could trust this friend to be open and honest about anything that came up for us. She consented. We haven't done anything, but when I talk to my gf about my feelings as they come up in preparation for seeing said friend in the future, she just replies "Okay, have fun," and doesn't show any emotional reaction. She seems to be fairly genuine about this.

I know that she loves me dearly, and I have done a lot of personal growth in order to show her through my actions and words that I am committed to our relationship, regardless of what happens in our lives or with other people. She is very open minded and understanding of non normative situations and relationships, and she herself really wants to have more physically (not sexually) intimate relationships with her friends than is typical. At this point, she has basically given me the green light and gave me her conditions (tell her what's going on and with who), and I told her that I would only be seeing other people when I am at my place of residence and not when I'm with her during those 2-3 months of the year. But I am not sure that I should be going forward with this and seeking out people given that she will not be doing the same for multiple reasons. Should I be taking her at her word and going ahead with seeking people out, or should I wait until something (what?) happens, or is this possibly a disaster in the making?

tl;dr long-distance gf says it's okay for me to date/have sex with other people when I am back home as long as I tell her beforehand, but she will not date/have sex with other people because she feels fulfilled and doesn't think anyone would date her. Should I do it, or cool it?