As for Liz, both times they had sex, she seemed to be satisfied, even though she didn't cum. She needs a lot of stamina, and not a doll, those two times she essentially used Kirito as a masturbator. Therefore, there was not even an emotional return to satisfy her. As for Alice, they didn't have sex. Actually, at that moment, I think she was upset not even because Kirito came quickly, but because he refused to have sex with her when she suggested. In general, Alice is not so dependent on a big dick, the "Shadow Fox" himself doesn't have a big dick. He himself complains about this during the scene, in the locker room, when he makes her give him a blowjob.
And it turns out that Kyoko, Liz (in the future), and Asuna are dependent on a big dick. And the rest of the girls, Sinon, Alice, and Sugu, are basically enough with what Kirito has.