LET HER DECIDE if she wants to be with Mr. D. You can’t go around saying, “Look sweetheart, it’s for your own good to marry D. You may not realize it now, but 10 years down the road, when you’re the amma of his 5 kids, you’ll finally realize that he’s a wonderful man and that you truly do love him.”
She needs to decide this for herself. She needs to figure out if she even wants to marry him. And if she doesn’t want to marry him, then don’t pressure her. She may find SOMEONE ELSE (besides Mr. D) who she thinks is attractive and will make a good life partner for her. A good friend won’t pressure you about decisions that will affect your whole life. You’ve made your suggestion, now back off and let her make her own decisions. In fact, just don’t even talk about Mr. D to her now. Let her sort out her own feelings for him on her own.