What's the Name of That Book??? discussion

Hi! So I'm looking for a mystety/thriller or fantasy book/book series that is well written, has a compelling plot and has a side plot of a slow burn romance. It should NOT be a love triangle. And the main premise of the story should be plot driven and not related to their romance. (Think Lockwood and Lucy from Lockwood and Co or King and Maxwell from the King and Maxwell series)
(Either way I'd like a happy ending with the two main leads getting together XD)
Also, I'd prefer it if the characters were in their 20s or 30s but I'm open to other ages too.

A Magic Steeped in Poison is a good duology, its fantasy with some side romance. the main leads are in their teens and its YA.

A few great suggestions; mixed genres, The Darkest Hour (KGI series) & Keep Me Safe (Slow Burn) by Maya Banks, Kiss of Midnight (Midnight Breed #1) by Lara Adrian, If She Only Knew (The Cahills #1) by Lisa Jackson, and Half-Blood (Covenant, #1) by Jennifer L. Armentrout.

The Kenzie and Gennaro series by Dennis Lehane are a good read .

Thank you for the suggestions everyone. Any more?

Please note you can bump your own thread 30+ days after the last comment in the thread, because this group is so large.

check out these lists if you like: https://www.goodreads.com/shelf/show/...
https://www.goodreads.com/shelf/show/...
https://www.goodreads.com/list/show/1...
https://www.goodreads.com/list/tag/be...
Hope that helps :-)

Any more?

You might like The English Agent by Clare Harvey - 2 side romances .