I do think there should be an option for both though. He did love Karen, but he also was feeling the guilt.

tough question i dont know i think maybe a little of both

I'd say it's a mix between both.

i think that deep down he always loved Karen and never really stopped loving her. It's just he let his ambition and pride get in the way of that and after seeing keith holding lucas before him, it made him bitter towards his brother. Yes he may have been feeling guilty towards killing keith, but really he was trying to fulfill the role of'father' that he wanted to be for lucas. He wanted to replace keith, the way keith replaced him.

Hard to be certain since I am obviously not the writer, only he truly knows! Lol, but i definitely think Dan loved Karen more than he loved Deb. I think choosing basketball over Karen led Dan to a life of bitter regret and pride that kept him from revealing his true feelings. His marriage to Deb was like a second chance at un-doing the mistake he made years ago, however his feelings for Karen were always there. Why else would he move back to a town that despised him for that decision, continuously meddle into Karen's life, and kill his own brother out of jealously? With Keith being out of the picture and Karen being Karen, Dan for once (for a short period of time) was happy, kind, a father to both Lucas and Nathan, and in love. I relate Dan's relationship with Karen and Deb to Nathan's relationships with Haley and Peyton. Broken men in need of love from a strong woman.