Decently written vampire series that have the same couple throughout it?

Preferences:

• evil/morally grey MCs
• the love interest must also become a vampire by the end of it.
• spicy

Series I already read:

• FBAA and its prequel. trashy, especially the main series, but it flows decently enough
• Night Huntress (didn’t bother with the last book since I was so disappointed with the sixth)
• blood grace. Love(d) this series though the main villain is so boring, wish it focused on its initial political intrigue
• age of vampires. Liked it, I have to finish it though
• gods and monsters. Love this series