Without saying anything else, just look at his current state—he's stark naked, lying in her room, on her bed! If she didn't have feelings for him, why would she allow this!
—Of course, although he thought about getting intimate with Jian Anning, he wouldn't act like Leng Yunlin and Ling Yichuan, who unscrupulously treat her like an ordinary fling— or to be more specific, like a casual bed partner, a woman to be played with and then discarded. Despite having nothing in common and the conflicts in their personalities and temperaments, he still hoped to maintain a relatively stable, sustainable man-woman relationship. If possible in the future, he wouldn't oppose her becoming his girlfriend, or even entering into a closer relationship.
To put it simply, she's more than a bed partner, but not yet a lover.