Why wont MIL let me hold my baby?

Im trying to figure out the psychology behind this. My MIL was holding my baby and she started fussing and it was stressing me out. I signaled to my boyfriend that I want her back so he told his mom to hand her to me. She tried to give her to my boyfriend instead and my bf said no and to hand her to me and she just kept trying to give her to him instead of me. My baby was looking confused where her mom was and sucking on her hands out of hunger. She finally handed her back when I said she’s hungry.

She did this the first time she held my baby too. She held her for like 30 minutes straight and eventually got tired of holding her but wouldn’t give baby back to me and gave her to my bf. It’s almost like she would get annoyed when I would go over to the baby while bf was holding her like my mil was kind of guarding my baby from me. Then when she held her again and she started getting hungry and she tried handing her back to my bf when she knows i breastfeed.

Im always interested in learning the psychology behind why people act the way they do so im trying to figure out her logic but i cant understand what difference she thinks she’s making by keeping my baby out of my arms for the measly hour and a half that she visits every once in a while