Complex sentence: In his grief over losing his beloved Kerry, Smithy changed into a very different person and later made the biggest mistakes of his life when he began having a relationship with Louise Larson, the wife of violent gangster Pete Larson.
Split into simpler sentences: In his grief over losing his beloved Kerry, Smithy changed into a very different person. Vulnerable and lonely without her, he later went on into making the biggest mistakes of his life when he began having a relationship with Louise Larson, the wife of violent gangster Pete Larson.