If you choose to just remain friends - you will get a drop in your relationship. His look-in moment is in Chapter 4, after the council scene. So if you do not lock-in your relationship, unfortunately, you're locked out of his romance.
There is - in chapter 4 after the council meeting. You need to actively pursue a romance with him to get this scene. If not, you're automatically locked out of the romance. Make sure that you join him on the balcony during Chapter 3 and only then will you get a lock-in option or friendship option. If your romance is negative something and you didn't get a choice to choose friendship, you've not gotten enough romance points to get the lock-in scene.