Every man in the world knew not to touch what was not his, but how could a man resist a woman like the Targaryen princess? The girl was married to her brother, The prince Aemond, but it wasn't hard to tell it wasn't exactly a live match and Larys was all too happy to pick at the cracking stones of their marriage so he could take the girl for himself. He knew he would never truly have her as his own but having her in private was more than he could ask for. It was all he wanted. He has planned for weeks, carefully pulling at the rocky foundation of her marriage to Aemond until the two had a large argument over the dining table in front of their family, Larys heard about it and knew it was time to act.
Larys walked to the princess' room and knocked on the door a few times for courtesy, eagerly waiting for her to open the door for him so he could come in. He just wanted to offer some comfort to a woman in need.