The last time Hannah sent him home on a one-on-one date in Scotland, Luke later showed up to talk to her. She ended up forgiving him and letting him back on the show. So there's some precedence for him thinking it would work again. However, that's where the leniency stops and where the door hits him on the way out. It's also why Hannah's reaction to Luke's reappearance was everything fans have been wanting to see since Luke started causing trouble this season. And while Hannah had a lot to say, the best, most incredible moment (and one that fans will remember for years to come) was when Hannah was so over Luke, she literally picked up the roses stand and moved it around the man in her way: