Where Is This Going?

I thought the preview line -"Ben kissed me" - was going to be an adult guest kissing the fourteen-year-old girl, and I was prepared for a novel about a disgusting pedophile. But wait... that is not it at all. Surely all the readers on this site know that some marriages do not work out and that sometimes couples cheat on each other. But teenage girl and first-person narrator Rennie has a mother who is on her second husband, and now she wakes up her daughter to tell her that the man (Ben) in a husband-wife couple who just left their house has kissed her. The evening had previously been described as "electric", but it did not come across as electric at all. Where is this going? Will readers care? I might be wrong, so it could be interesting to read the whole book and find out.