IS A BOYFRIEND?

A LETTER: EXPLAINING A PROBLEM
IS A BOYFRIEND?

I’ve had a problem recently. My best friend Marta met a guy a month ago. They’ve met a few times and I think that she likes him. But, two weeks ago, I saw the guy with another girl.
I’m worried because I saw that he had another girlfriend, I think that my friend should be better when she had split up with him.
I don’t know what I’m doing. Can you help me please?