Several appealing points about this set-up. From the outset, Wyatt realized that he doesn't have to kill either of the serial killer's parents. As I've often said, to get the grandfather paradox going, all you have to do is prevent your grandparents - or parents, who will also do - from meeting. You don't have to kill them, and, actually, you don't even have to stop them from meeting - just stopping them from mating will do the trick.
Wyatt, decent person that he fundamentally is, however, plans just to stop the serial killer's parents from meeting. But because things can often go wrong in time travel, and so often do in Timeless, he's soon down to no choice but to stop them from mating.
He manages to do that, just barely, but then as he's chasing the guy (played by Drew Roy - good to see him back from Falling Skies), the father of the serial killer hits his head on the curb and ... dies. So Wyatt has now, through no fault of his own, gone to the brutal essence of the grandfather paradox and killed one of the progenitors.
I had a feeling Wyatt's love wouldn't be saved anyway. My theory was that killer's mother ended up sleeping that night with the other guy in the bar who wanted her, and those two were the serial killer's real parents (which fact got jumbled in the birth certificate or whatever that Wyatt saw). Who knows, maybe that was in an early draft of the script. But what happens is actually better. Two of the three women killed originally by the serial killer are alive when Wyatt returns to the present. Just not his true love.
What this tells in a sad but eloquent way is that changing events in time is more complicated than even a grandfather paradox story can accommodate. Who knows why Wyatt's wife was killed - and by whom. The universe is fundamentally unpredictable - even for the time traveler.
But I predict Timeless will be on next week, and I'm looking forward to it.
See also Timeless 1.1: Threading the Needle ... Timeless 1.2: Small Change, Big Payoffs ... Timeless 1.3: Judith Campbell ... Timeless 1.4: Skyfall and Weapon of Choice ... Timeless 1.5: and Quantum Leap ... Timeless 1.6: Watergate and Rittenhouse ... Timeless 1.7: Stranded! ... Timeless 1.8: Time and Space ... Timeless 1.9: The Kiss and The Key ... Timeless 1.10: The End in the Middle ... Timeless 1.11: Edison, Ford, Morgan, Houdini, and Holmes (No, Not Sherlock)! ... Timeless 1.12: Incandescent West