Both end up in bed with the people they love - Frank with his estranged wife (Raimy's mother), Raimy with her fiancee from the alternate reality in which Frank died, but was changed because Raimy helped save him with the knowledge she had from the future.
This wasn't an easy course of true love for either couple. Frank's wife has been resisting him all season. Raimy's fiancee has gone from not knowing her at all to sleeping with her in the last episode, but ushering her out of his house at the beginning of this episode because his fiancee from this reality was coming by. Fortunately, he's come to his senses - or the feelings he had for Raimy in the other reality - and is breaking it off with the new fiancee to be with Raimy.
The love Frank and Raimy are finding are making them even more determined to stop the Nightingale. They both were actually always very determined. But now Frank has an additional very powerful reason for not wanting his wife to be a victim of the serial killer. And, getting back with her fiancee is reminded Raimy more than ever that her mother was alive before Raimy started playing around with time to save her father.
Fortunately, we also now know who the Nightingale is - Deacon Joe. We'll have to wait until January to see how Frank does in his vow to kill him - I'm looking forward.