It's possible to have one of the girls get Girlfriend status and then friendzone them, they'll take a hit to their LP, and you can apologize to get them back to Friend status. The important part is that if you have an active relationship status (Girlfriend, Sex Slave, Mistress) with any other girl (and Samantha didn't introduce you as her bf) you admit it when she asks, and you've broken up with them before she brings it up again. The exceptions to those are Lexi, Audrey, Palla, and Bree if she's your Girlfriend (NOT Sex Slave) while in her Cafe Maid path and you went through the event where they talk with each other at the Uni. Also, you cannot break up with a Sex Slave, so unless it's one of those exceptions you're SOL (Cassidy is an issue, bc through her event you're forced into having her as Sex Slave/Mistress, and the only way I've found around it is to delay your promotion, thereby delaying the initiation of her path).