Anna was unjustified in her anger over April's party

I'm on rewatch 4 or 5 and Im realizing that when Anna confronts Luke she keeps calling lorelai his girlfriend. It irks me because until April inserted herself into Lukes life they were on the fast track to get married. Its so ridiculous because April did insert herself into his life. He didn't know about her, and she's smart she would have known that there would have been a chance of him wanting to get to know her after he found out about her. He didn't seek them out and shove himself in. He stepped up once he found out about her and tried to be a dad for her. Anna is way overprotective of her and Luke has given her no indication that she needs to be. Her flip out on Lorelai for the party is just another example of that. His fiancée helped him with a party. The woman he was planning to spend his life with. She wasn't a girlfriend that he was seeing casually Luke had been actively pining for her for years that's evident in the whole town.