Season of Change by Lisa Williams Kline

Norm and Lynn are having problems. Big problems. Rather than hide from the issues, they go on a marriage retreat together while Stephanie goes to cheerleading camp and Diana stays with her father. But when everyone returns, things seem worse than ever. So bad, in fact, it looks like Stephanie and Diana may not have to put up with each other anymore, which is what they wanted all along.

This final book in the Sisters in all Seasons series brings the story of Stephanie and Diana to a close, and shows what happens when two opposites become friends, and maybe sisters.