Yeah, that's why i really find people who thinks a Dylan+Ellie route will happen anytime soon lacking on awareness. It's like they didn't get any information about Dylan and Ellie's relationship other than the last one (Ellie asking Dylan's help).
Hell, she even dislikes the idea of having bath after him in the same bathroom. He probably spanked his meat while spying on Ellie, maybe quite a few times, when they were younger. That's just a guess btw, it can be even worse or it can be nothing at all (i don't think it's nothing, Ellie reaaaally dislikes her brother).
At this point, all we have is speculation about why Ellie dislikes Dylan so much.
It's easy to add in your preferred flavor:
I Don't Like Dylan so he must have done many bad things to Ellie.
I Like Dylan so Ellie is being unreasonable.
In the End - we don't know!
The author of the story has set up tension between different characters (Ellie and Dylan is a major source of family tension but there are others including the tension between Sophia and Liam - Liam is not paying enough attention to his wife and her eyes are wandering..., then there is Liam and Dylan where the thing Dylan is most proud of - his soccer playing skills - are always ridiculed by his father - and 'best' male role model.)
It is his artistic license to resolve the tension as he sees fit.
_____
We have seen several bonus story lines between Ellie and Dylan where their feud seems to be ratcheting down a few degrees.
If you don't like Dylan, you typically don't like or agree with this part of the story arc - L&P is selling out so Dylan can bone his sister or L&P is selling out because Dylan is so popular.
If you like Dylan, then this is part of a logical healing process that typically takes place between siblings.
_____
What if L&P is maintaining the tension between family members as part of the story??
For those who actually think that the Dylan and Ellie disagreement is permanent and can never be resolved - is that based on your own experiences or just your desires re: you like Ellie and dislike Dylan?
Real life - brothers and sisters fight as teenagers and many heal their relationships as they get older. I come from a large family and I've seen the healing take place, prompted by different things - I played soccer and a brother 1 year younger started playing. In time, it was more fun to beat the other team than to beat on each other. One brother and one sister refused to back down when they disagreed and it was not uncommon to have them come to dinner with the sister's cheek bruised and the brother's cheek with claw marks on it. They are great friends now and yes - it did not happen instantly, but turning points actually occur.
If you are an only child or there are significant years between you and the next sibling, your personal experiences are likely not going to provide the tension I saw growing up... or the tension that L&P has written - yes Written - into his creation.
So - why don't we let L&P tell the story his way, creating tension and doubt as part of the journey and see how these are resolved through time?