My 2 cents… I would share a seat if you think both of you could get adequate rest that way. Otherwise, book 2 seats, but make sure they are across the aisle from each other.

I just flew j class from SFO to SIN with my husband and 5 year old. My husband was across the aisle from our son and I was in the middle section next to him. I found it very difficult to assist him with anything because it’s a pretty far reach from seat to seat (especially when your tray table is up) in the middle and you can’t easily get over there physically if you need to. It was easier for my husband to help him from across the aisle, though it wasn’t easy for my husband to actually see him.