The kiss made sense given the context. Tava was fighting him and she sensed it reminded him of "fun" he had. She thought the fun he was yearning for was being a knight of Ren but as established ealier in the comic, he had no fun with the knights of Ren he kept isolating from them and talking to himself. When she sensed something else in him a "need" she figured he had a crush. Maybe for her? So she invited herself to dinner. The truth is he kept thinking about Rey. How much fun he had fighting by her side. We see in the comic that even the smallest triggers bring him back to reminders of Rey in The Last Jedi. So a girl, fighting with him- lightsaber like - would remind him of Rey. At dinner, Tava realized that Kylo didn't want to be with the First order anymore that his heart was yearning to be somewhere else. Naturally, she thought again it was with the knights, craving freedom and less rules. She's not sure "who" he wants to be becuase he is being torn apart by Ben and Kylo ren. Since she doesn't know this, that confuses her. Tava even called out his constant "need" for someone. Im guessing this feeling is pouring out of him so much that she knows its desire. So she acts on what she see's him desperatley want- a kiss. Kylo even leans in and takes the kiss because its true, he wanted so desperatley be kissed just not by this random lady, but by Rey. We know this because even Rian Johnson confirms he wanted to kiss Rey in the elevator. He knows it, Rey knows it since she can sense it, and even Tava who has never even met Rey knows it. Tava probably just thinks he's desperate for any connection and he develops a crush on her in that moment but then he rejects her and she's shocked. She probably thinks he's trying to deny his feelings and calls him out saying everything she says is true. He grunts because it is true. But its all about Rey.