They can fix that in one re-write. Luke and Robert schemed to make Luke Ethan's father to protect him from some unknown threat to Robert. Holly was in on it, and Luke lied to Lucky about it. Perhaps he couldn't tell Laura the truth because she was in a catatonic state and too fragile and unreliable to understand and keep the secret. I don't care how they re-write it. Just do it. Luke would NEVER cheat on Laura. Perhaps that is what is in the letter that he wrote to her!
I didn't watch the scene, because, as usual, I'm way behind on GH and am hoping to catch up.
I'd love for Ethan to be the son of this supercouple instead of ours. It's always the option that made more sense. And I know R&H fans would be absolutely thrilled.
But unless they find a way to rewrite the affair that Luke and Holly supposedly had in the 80s, after Lucky was born, then this does nothing to repair the ugly rewrite to L&L's history. The damage was done to their once well known fidelity the moment it was revealed that Luke could even possibly be Luke's son, no matter who his dad actually is.