I answered this in the main comment section, too, but in case anyone else is having trouble:
For those three, either come home with Marco from the party the night before, or leave another evening hangout early and catch him jerking off. You must ask him to finish in the bathroom.
In the morning you'll text him. First send the friendly version of the message, and then later in the update the first two will unlock. Then repeat the steps above, only send a sexual text. The third CG will unlock in the same place as the other two.