The thing is "giving in" can mean two things here -- giving in and working with Seymour instead of rejecting his offer, or giving in to his sexual advances. You didn't really specify which of those you meant.
Also as far as i can tell even in the case of giving in sexually if in close relationship isn't really automagically turning Lena into some "vapid gold digger"; at the very least she monologues about cheating on Ian and potentially Holly, and tries to figure out how she should proceed.
I think it was clear, giving in to working with him isn't very extreme, especially early on. Of course I was referring to the sex. Don't leave out the monologue about how Seymour can give her everything she needs, when up to that point she was wary in most of her thoughts, so an extreme change.
My point is it is a game of extremes, romance, wealth, sex, cucking, cheating, there is not a lot of middle ground or hybrid pathing, if you choose everything for a certain path, it all goes to an extreme. This isn't a bad thing necessarily. With everything that is going on, it would be 100 chapters to have less extreme paths along with the current stuff.