Can you post a photo of your plant?
Which of the leaves are yellowing and dropping? Typically, my Aeoniums start to drop the outer leaves when our temps are getting too warm. It will tighten the rosette, like curling inwards , slow down a bit in growth and will keep it that way, and resume more active growth when Fall season returns with its cooler temps . When I see this happening, I really am careful in watering, since the plant is in a semi-dormant phase.
Also, did you notice if the plant has made any bloomstalks? Aeonium tabuliforme is monocarpic, so it will naturally die after it blooms.