A locked symbol on the heart gauge might simply mean that you have to trigger the next scene with Bree before you can rise it further. As it was metioned before, there is a very good wiki that explains how to raise love and kinky for the girls.Maybe I'm playing it wrong then who knows ¯\_(ツ)_/¯.
I just remember the last thing I saw was one of mc best friends showing up to the house claiming hes going to do dnd and trying to invite mc because one of the people playing freaked the fuck out because they weren't taking there meds .
Then he turns to bree eyes them up with the most thirsty look on his face and you can imagine the rest. Next day theres a locked symbol where the heart gauge is and I didnt notice intill 10 DAYS AFTER THE FACT.
Had to start the whole game over :l
And no, the DND guy can not take her away, there is no route for it.