is this an overreaction?

I'm interested in a woman who I got to know before she quit with her boyfriend months later. Since I grew aware of how she dealed with it, I told myself she should heal first. But shortly afterwards, a friend of her best male friend joined the group, first growing accostumed to us. Then at some point when her best friend left for the night, he told me she'd stay a little longer, talking to his friend. I decided to stay with the two and another guy, and got the chance to listen to what they talked about (joining in here and there, just like the other guy). At some point this friend had straight out asked her if she had a boyfriend, and she became quiet and said that she'd still stick to her ex (though she as the one quitting).

I told myself that he'd get the message (figuring she must have friendzoned him). Yet weeks after that night, I overheard the two talking about going to museums together, later he even tried to invite her to a trip to London. She seemed to set a boundary like "but no more than this" (yet not in an irritated tone).

Is she treating him like a friend only (despite his attempts) or is there more to this?