When I focus in on Marc I do get a psychic vibe he has crossed over boundaries with other women at times. I’m not seeing that he has cheated necessarily, but there are boundary issues there. I’m not sure about Tasha. With Tasha, I would assume it hasn’t happened until you know for sure.
To get things going in a better direction, I see that focusing on strengthening your bond is your best bet. In this specific situation, if you confront him without proof it’s not going to help anything.
On a different note, have you ever thought about getting into nursing or teaching? I keep getting a psychic vibe about you doing something like this.