That page xdoop linked to mentions this: "She returned home to find that Terry Long had left her, with their son Robert. Terry became increasingly concerned with the dangerous life Donna led - and how it affected his son's life."
So, did he leave her? Yes. But he didn't really leave her because he didn't love her anymore, he left her because he was afraid for their child. I mean, that same page mentions "Villains and disasters struck their new home." just a bit before the part I quoted. If I were a parent and felt that my spouse's actions (or in this case, lifestyle and / or calling) threatened my child's safety, I'd leave too. Granted, I'd do it in front of him or her, not behind his or her back.