It's very strange that Shadowheart is the one acting this way. If you're having an affair with another character, she doesn't act like any kind of sexually active character at all. Of all the companions, only she and Karlach don't try to have an affair with Tav, with Karlach at least saying at the party that she "would like a hot guy", but I never heard anything like that from Shadowheart during the whole game, not a single word about sex, on the contrary, in mini-dialogs between companions she fends off attempts of other companions (e.g. Will) to flirt with her. It's really surprising, and seems like some sort of logical inconsistency.

One life, one love - until the world falls down.