I tried this on my step niece all throughout our late teens and early 20's. Everytime she would end a relationship i was always the one whos shoulder she would cry on. Id tell her she was too good for them, a beautiful person inside and out, that any guy would be a fool to let her go. Id tell her how jealous i was that they got the opportunity to have a girl like her and how angry i was that they messed it up. I even came outright a few times and told her i dreamt about her and i living a life together and that was insanely attracted to her. None of it got me anything but a smile and a thank you. Sometimes no matter how hard you try, they just arent into it. Unfortunately.