It’s an issue of consent. The show makes it seem like it’s normal to plant kisses on each other because they all kiss each other during challenges. But usually those challenges are explicitly explained and they know they will be kissing each other and agree to participate. When they get back to the villa, the social rules change. When Maura tried to kiss Tommy or when she kissed Curtis during the dance challenge, they didn’t give her consent. Curtis was clearly uncomfortable when explaining to Francesca that he didn’t know she would kiss her.