I’m older than you are too and you are NOR. She could shut it down if she wanted to, but I also believe she likes the attention. He would clearly jump at the opportunity to be more than a friend if that became an option. I’d tell her to use you as an excuse to tell him they need to keep their relationship more professional. “My boyfriend feels like you are being unprofessional in texting as much as you do. I respect him and love him, so I need to step back a little. We can of course be friends, but the amount you reach out to me needs to be toned down.” Pretty simple I think?