I got with an old friend like this in almost identical circumstances with similar behaviour from him which I minimised, as I had low self-esteem significantly because of my relationship with my dad. It led to years in a miserable relationship and eventually my therapist helped me see my worth and I broke up with him.
If I look back to what might have helped make me think of it a different way:
Explain you respect her decisions but kindly suggest that it's good to reflect on whether a guy's actions align with his words - I was far too focused on the crap he said (deep chats 🙉) and didn't think about how disconnected this was from his behaviour.
Ask her how she would feel if her friend was being treated this way. She might find it easier to be objective about it because we tend to have higher standards for our loved ones and friends than we do for ourselves.
Encourage her to keep up with her support network no matter what: time with you, her friends, sticking to her career goals, hobbies, all of this helps ensure her world doesn't shrink the way mine did.
If there's anything therapeutic she might consider - 1-1s, self help, wellbeing apps, affirmations cards, self care tools, anything at all could help her start focusing on her own needs - even little things could make a difference.
Good luck to both of you xxx