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It sounds that she wants to keep her family and that there was a fling. It is not uncommon for individuals to believe that they will find something out of their family (after all when partners stay together for many years, the relationship can become stagnant) This does not necessarily imply that they don't love each other. Every relationship goes through different stages.
It is quite possible that she had found herself in this situation of seeking or hoping to find something out of her relationship.
You've mentioned that you separated from your ex but (did not mention if she did this as well from hers)
Either way, she may also have become scared of another commitment and used the kids statement if they ever made it as an excuse.