In this visual novel, you have the option to stay on a character's romantic path, or get off of it at certain points if you prefer.
And yes, indicating you don't want to be romantically involved with a character anymore means you don't get to give her very erotic massages anymore either. Note that the game will give you a clear warning when a choice leads to leaving a character's path.
As to characters in this game occasionally kicking you out of the bathroom or otherwise doing things for their own reasons that do not include the MC, that's life. As any guy who's ever shared a household with any number of women can attest, you are not in control here, buddy.