Should my 43 yr Fiance be jealous of my 3 yr old granddaughter?

We took custody of my granddaughter a year ago. My Fiance tells me she wants me to be "on" for her like i am for my granddaughter. I was made aware of this and tried really hard to be to take notice when it happened. I feel that my granddaughter needs the extra attention at this time in her life since she didn't have much with her parents. My fiance says when i want a relationship with a "Woman" not a child............then call her. Am I wrong to feel my granddaughter needs more now?