For everyone struggling with the stress and approval mechanics, here's a few tips that I think make a big difference.
1) Try to learn the schedule. The mother is on the same time table every day, and she switches locations at the top of the hour. This doesn't happen every hour though, as sometimes she's in the same place for a longer period of time. This can help you plan accordingly if you're trying to save stress for a specific event later in the day, or line up your relaxation (see point 3).
2) Use your consumables. You should be grabbing coffee every morning and a meal from the fridge whenever they're available. The coffee is available every morning until a certain time, and the meals are available after the mom finishes in the kitchen. You can get more than 1 meal a day.
3) Try to use relaxation techniques with the mom present when possible. At certain times of day, the mother participates with the MC in the shower and when watching TV. These intervals refund you most of the approval you would lose for relaxing, so it's basically free stress.
4) Similar to 3, there are times when doing the chores will net you a scene. If the mother is in the room where the chore takes you (so the laundry room for laundry, the living room for mopping, etc.) you'll get a scene. I don't think this increases your approval gain, but it's relevant later when you're trying to raise sexual tension.