If you're at the end of the year then you need to restart, even after you start dating a boy you need to progress the relationship with him afterwards in order to get the good ending with him. You need to spend time with them on the week days as well, sometimes you'll get the reused dialogue of spending time with them but if you persist you're occasionally gonna unlock new scenes with them and you need these scenes in order to get to the confession scene. So keep choosing to spend time with Shiba at the VA studio, mall and restaurant during the week days, you need to unlock at least one new scene with him per week till you finally manage to progress your relationship with him enough to become lovers.