Have your fiance participate more in her care. Like feeding her, walking her, bathing her, etc..
She will come around. You've only had her for a few weeks, right?\
My Abby is most attached to me, but Daisy LOVES my son! He's 20 yrs old and she is just crazy about him. She does prefer for me to take her out to potty and when I lay down, she goes straight to bed with me. I think my son is "the fun guy", but she loves and needs her Mama