Antoine talks about going to the restaurant near his apartment and kissing the owner (whom he's been sleeping with). He didn't want to kiss her, but did it out of politeness. He even took a moment to touch her under her skirt while they hugged, but his heart wasn't in it.
All he thinks about it Rollebon and how futile his whole project is.
Next thing you know, Antoine is waking up in the woman's bed. How's that for a meaningful relationship with another human being?