When she was talking to sai and made that fake smile ,she didn't mention love . Where you got that from ?and sai said her words are sincere .
She rejected that shinobi at the beginning of the war, saying she was in love with Sasuke (but never said his name, it was implied by his image behind her). When Sasuke finally showed up for the battle after her confession days earlier, instead of reacting like one should who loves another, she didn't trust him. Sai noticed that when he asked her about him. I think the love she has is what she's held onto for him since they were kids, but she's realizing it's not as real as she thought. And that happens when you grow up.