I just did my first play through of the first Mass Effect. I tried to play through as I think I really would in real life, so I was really polite and compassionate to everyone, but also wasn't afraid to get my hands dirty from time to time, and I was cold and pragmatic when I had to be.
Anyway, in keeping with this polite, compassionate, but sternly efficient demeanor, I chose to romance neither Ashley nor Liara. A Spectre Agent rescuing the galaxy from certain destruction doesn't have time to mess around!! Letting Liara down nicely was straightforward enough, she's a huge nerd and isn't smooth enough to flirt and sidle into it, so when she straight out asks you if you like her you can just politely say no.
Ashley on the other hand....
Girl's clever! The writer's somehow tricked me into romancing her, because I genuinely wanted to hear all of her interesting stories about her dad and the poetry and all of that. That, and the only other option is telling her she's boring or to shut up, and that's not polite and compassionate at all.
So, how do I hear all of her stories, be a polite and compassionate dude, but also make it clear as early as possible that it just isn't going to happen?