Monkey branching? Do girls do these things?

[Anonymous]

I work with a girl for 5 years always good friends
She has a boyfriend for 4 years but lately I heard things are bad
So we started flirting lately and become attracted and she sends me sexy snaps like her in a bikini or she replys to my general snaps saying I look good or shows her cooking food

Another guy flirts with her at work too but she hardly sends him private message s saying he looks good on Snapchat. it all has me confused...
Even tho I like her I think the other guy at work could be banging her while she's living with a boyfriend I haven't proved this but my gut says..

Do women monkey branch like this trying to get any guy while living with her boyfriend to move on?
What do I do.. I like her and would like to bang her
Strange situation? what does she want

Updates

+1 y

Any details?

[Abraham95]

Really annoying confusion