As painful a decision divorce is for grown-ups, it's equally (and perhaps even more) confusing for young toddlers. Adults often make the mistake of thinking divorce does not have an affect on very young children—that kids before preschool age can't understand the complexities of relationships, so the dissolution of theirs isn't really worth discussing.
Not so much: While it's true that kids this young are not able to comprehend the dynamics of why Mommy and Daddy aren't going to live together anymore, they absolutely will feel the effects of the resulting changes. Two year olds are normally dependent on routines and have a strong desire for things to be the same as usual. During divorce, a significant attachment figure that your child relies on will no longer be available to him regularly—this will be a big adjustment for your child, but one he can make with extra support.
What They Understand
Your child's greatest awareness will be when either mommy or daddy is no longer living in the same house. He or she will wonder where the other parent is and may ask, "Where's Mommy?"—even if he just received an answer a short while ago (and a half-hour before that, and an hour prior to that …). And even with repeated answers, toddlers may find the idea that their world has changed bewildering. In fact, only once they reach school age will children fully understand the concept of the term "divorce."
Around 24 months, toddlers are sensitive to and pick up on strong feelings the adults around them have—in fact, even young babies can pick up on a caregiver's stress. That said, egocentric young children will not be able to understand or react to why mom or dad is upset.
When deciding to break the news to your child, remember that young toddlers live in the moment: While they are be able to grasp the changes that occur in their immediate routines, they are not able to understand the idea that something will be happening in the future. They certainly can't comprehend that mommy and daddy will be eventually getting a divorce—so it is important to tell them only when plans are definite and moving forward. At that point, your toddler will need a clear and short explanation about how the change will affect him.