She is in awe of Wallace and she doesn't want to disappoint him
Luv is living in awe of Wallace, she looks up to him and even thinks that he has named her:
Luv holds back. Knows better than to help without asked as
he begins his examination.
NIANDER WALLACE (cont’d)
Bring the one for micronics, would you,
luv.
Ah, “luv.” A diminutive. Not a name at all, though taken
for one. Luv brings a small wooden box.
...
The electrodes fit into wetware receivers within and... the
device glows to match the new light in the Barracudas’ eyes,
enabled.
Luv’s hands shake as she closes the box. Beyond respect, she
lives in perpetual awe of him.
-Final Shooting Script, Blade Runner 2049 (2017), Green, M., Fancher, H.
Once Wallace is done with his speech about wanting to take over the universe, he tasks her with bringing the last piece of the puzzle:
THE MODEL COLLAPSES.
NIANDER WALLACE (cont’d)
His last trick. Procreation.
Perfected... then lost. There is a
child. Finally unearthed. Bring it to
me. Bring it to me. Bring it to me.
ON LUV: An eye waters at the thought of disappointing him.
LUV
Sir.
He reaches behind his head, removes the HALO. Preferring the
darkness.
NIANDER WALLACE
The best Angel of all. Aren’t you, luv?
ON LUV: Her jaw sets. She will not disappoint Mr. Wallace
-Ibid.
So you see, Luv is in perpetual awe of Niander and even petrified at the thought of disappointing him.