Ultimately Gabby was an adult. If Brian left her somewhere because he couldn't cope with everything anymore or he missed his mum or for whatever reason, he legally had the right to do that. But even if he broke off their engagement and even if she did say "take the van, I can't drive hundreds of miles home alone", he had and has a moral responsibility to do everything he can to leave her in a safe place where she can make her way home by herself. That means ensuring she was in a town, near an airport, railway station, bank etc and I would also have expected him to at the very least text her family so they know what's happening, where she is and can consequently help her get home. What's strange is that in the police video, he wouldn't shut up. He tried to do the whole poor nice man with a crazy woman thing and frankly the police encouraged this. Now, he's hiding behind his mummy and daddy who apparently won't let the police speak to him.