I know endgame is mostly PvP, but we don't mind! We had a blast getting sidetracked during the campaign breeding perfect tems and TV training, often splitting up solo for that and still having fun. He'd catch every Tateru during stamina training and hand me off the good ones for my Momo breeding, and I'd do the same for him.
The amount of content we got in those hours were more than worth the price of admission, in our experience. We laughed through dialogues, adjust our builds to each other, roll our eyes and scream at the TV over the stupid Koish fishing event, and basically had a blast. That's not counting the hours we spent researching combat and pvp, building teams online and talking about the game.
We're now excited to get into the endgame content and really focus on building tems we love. Definitely a wonderful game to spend time with a loved one.