Is this girl being unfaithful or this is a standard?

So before anyone complains, I am forced to watch these two because I sit near the dude at work...

So i work with a girl (who has a boyfriend) and a dude. They seem very playful around eachother and she frequently visits his desk. They tease eachother, flirt and joke around.
I noticed she lets him do whatever he wants. He took some paint on his finger and took her hand and was drawing on it. Another time she came hitting him with a piece of string and he took it from her and tied her hands together and touched her face. Today he was playing the "fortune teller" with her hand while caressing it...

is this ok for a girl with a boyfriend?
Is this girl being unfaithful or this is a standard?
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