May I ask? Did you play in B! Logan route or T! Logan route? Because 2nd heart in available for T! Logan only.
His second heart is indeed only available with T!Logan, and you need to visit his house somewhat after 16:00, there is a chance to find Logan there, but you need to choose to be there for Ste and suggest his sex offer another time.
(The reason why it can't be done on B!Logan route is because Logan is taking his dick instead)