This worry was covered in threads the first week BLT was open. I believe the consensus was that the pool is far enough away from the building that it's not affected until late afternoon. And then the shadows would creep into the pool. Your DH wife could move to the beach area which is further away from the building. Or go over to the CR pool which might not be in shadows as early as BLT since that building is shorter.
She can also pool hop to another resort.
Here's the Pool Hopping rules that are posted on the member website:
Pool Hopping Information for 2009
Whenever you are staying on your Membership at Bay Lake Tower at Disney's Contemporary Resort, Disney's Animal Kingdom Villas, Disney's Beach Club Villas, Disney's BoardWalk Villas, Disney's Old Key West Resort, Disney's Saratoga Springs Resort & Spa, Disney's Vero Beach Resort, or The Villas at Disney's Wilderness Lodge, you and any Guests staying with you, are permitted to use most of the other Disney Vacation Club and Walt Disney World® Resort hotel pools (in addition to the pool at the resort hotel at which you are staying) if they are not at capacity. If the pool you are visiting reaches capacity, you may be asked to leave in order to accommodate Guests of that resort hotel. Please check with a Host or Hostess at the Front Desk of the resort hotel you wish to visit before you go to find out about pool-access availability. You must present your current "Key to the World" card with your "
DVC Member" designation on it to use the other resort hotel pools.
Pool hopping is not available at Bay Cove Pool at Bay Lake Tower at Disney's Contemporary Resort, Uzima Pool and Samawati Springs Pool at Disney's Animal Kingdom Lodge, Stormalong Bay at Disney's Yacht & Beach Club Resorts, and the leisure pool at Disney's Beach Club Villas. There are no exceptions to this policy. As a reminder, during times of high occupancy, please be mindful of the limited number of pool chairs available, and refrain from leaving towels or personal items on unoccupied pool chairs.
Resort hotel pools may become unavailable from time to time due to capacity limitations. Due to the high occupancy that is expected, Disney Vacation Club Members and any Guests staying with them may not pool hop during the following dates*:
November 23-29-, 2009
December 12, 2009 - January 3, 2010
February 14-20, 2010 (Sun – Sat)
March 27 – April 10, 2010 (Sun – Sat)
May 28 – 31, 2010 (Fri – Mon)
June 27 – July 5 (Sun – Mon)
Sept 3 – 6, 2010 (Fri – Mon)
Nov 22 – 28, 2010 (Mon – Sun)
Dec 12, 2010 – Jan 2, 2011 (Sun – Mon)
*Other restricted dates may be added based on projected pool capacity