NC for a year now wants to explore something whilst having unrequited feelings

[Shaun123]

Have a dilemma which needs advice. A girl I have been hanging out/hooking up with on and off for 5 years is back after NC for a year, whilst im not too worried on that- im realistic on this as she lives in USA and me UK and its how it has been as she just sucks at communicating with everyone- I have been helping her with her work arrangements in recent weeks as we work in the same industry. We exchanged flirty messages like normal and when she arrives she arrives with a live-in boyfriend whom she didnt mention on our communications until i met her one to one for a drink. I havent met the guy as i chose not to meet or at least limit meeting him as she told me that he was aware of me and knew on our past. She tells me she is unhappy in the relationship and it seems hes not what she wants e.g. hes a lot younger and "isnt as mature, advanced, "got his **** together" as me" etc Ive met her a couple of times in the first week she got here and things have been great and im really starting to like her for real now but our meetings have been short and we've kissed a little bit but that was me initiating. she has told me she is thinking of finishing it on her trip here(shes here for a few months) and exploring what we can do afterwards. whilst i feel really bad for the guy as ive had a similar situation in the past im really starting to like this girl and see where it can go(shes also looking into moving here full time), i told her i need to be removed from the situation now but im unsure of where it would go as a) shes obviously is ok with cheating in a committed relationship AND which is the biggie b) she told me she has feelings for another guy whom only wants to be friends. All very bizarre, any advice would be appreciated