It's not very well-known that when a person gets married, if they've written a will then that will is no longer valid (except in very specific circumstances). It's perhaps even less well-known that when a person gets divorced, their ex-spouse is automatically cut out of a will they have written.
All good? Perhaps, but perhaps not.
The first question is, has enough consideration been given in the will to what happens when the second spouse dies? If it is a DIY or cheap internet will, then maybe not. Also, if one partner compromised on guardians for the children when the wills were written, then they may want to update their will to name the ones they really wanted.
As with all major changes in life, divorce is a time when your will absolutely needs a good review to ensure it still meets your requirements.