ITA Passionflower,
To take it a step further, asking why it would be necessary to kill Kyron if TH and Dede were so close as to be a 'couple', I believe Kyron posed a threat to Terri, and to maintain the lifestyle she wanted, she had to get him out of the way which resulted in his death.
She had all the financial security marriage gave, and during the day could live the life that made her complete. Anything that could have ended that perfect situation for her she would eliminate as I think she wanted her cake and eat it too !If Kyron saw or knew about something he shouldn't have and threatened to tell his dad, Terri knew that would be the end of the marriage as Kaine would never accept her putting his child in such a position. For Terri she might have realized it was only a matter of time till the truth came out about whatever it was that was so bad a child would recognize it, and she made that icy decision to kill Kyron.
If these 2 women did have this relationship, I think the bond between them would be solid enough to where Dede would help with anything. The situation benefited her as well IMO as she also reaped the blessings of Terri's financial situation. She was a gardener with little income I believe. And without the perks Terri brought to the relationship, they would have a very hard time managing the lifestyle they had become accustomed to.
I remember so well during the Scott Peterson case when Dan Abrams on MSNBC interviewed a psychologist who stated the main reason people commit murder is to remove the threat so they can have the lifestyle they want for the future. xox IMO