Nope, you don't. That was a different path. You can be nice to her and do some fun sharing.
I think you do have to be rough at first, but it's not that bad. You need to avoid having more love points than sub points at a certain point, and that requires that you're at least cold to her interest in you, at first. In order to not get into the love path, you also have to take her virginity in a rough and heartless way and, later, tell her you don't love her, you're merely attracted to her. Then you can start treating her better, but I think there's another point where you need to reject her in order to avoid getting into the love path. After a while, though, you're not given the option to be in the love path again, and can start being more caring to her. It's a rough few game days if you're a softie like me who melts with Emilie's inner thoughts and (partly shattered) dreams of love. But in the end, if you later accept her as your girlfriend, it feels like you were a pretty rough around the edges kind of guy (an asshole, actually) but she managed to break in and steal your heart. And for Emily, it feels like her patience and dedication pays off and she succeed in earning the heart of the guy she had a crush on. 90% or 95% you'll be perfect lovebirds on the girlfriend path. I didn't play the love path or the full NTR path.
Girlfriend in the sharing route is a pretty satisfying path, and once that initial thickness is overcome, your character can be pretty stout, loving and tolerant with a ton of stuff Emilie does (you always get the option to refuse every time, but I accepted everything, even when she got propositions for, or even proposed herself, stuff that you had agreed would be off-limits). You always seem benevolent rather than weak, get a kick from Emilie's adventures and she never stops loving you. Not to mention that she has her own fantasy of sharing you with other girls.
In the end I managed to marry all the girls but one, and shared multiple of them, something that some people don't like to see mixed. In my defence, I'll say that harem+NTR is a good example of the kind of "rules-bending" that I like, if it's well-written (even fantasy needs some logic to achieve the "suspension of disbelief", pardon the commonplace, that makes you immerse in the story).