As I have nothing to base anybody else on, should I ask her straight if there is anybody involved?

I asked this a few weeks ago when she dropped the bomb, but she totally denied it, saying it was about how I have acted.

I have to keep focused on me and not think about another person.

I am happy in me and need to keep that my priority.

It's just the mild flirting, walking round half dressed that has me confused, it's like she wants me to react, but is it so that it can be used against me??