HarperCollins has all 6 of
Jocelynn Drake's Dark Days series on sale for
$0.99 each. I'd call this UF with strong romantic elements. Check your favorite retailer (I'm waiting for BoB, to catch the additional discount).
.5.
Bound to Me (novella)
1.
Nightwalker
2.
Dayhunter
3.
Dawnbreaker
4.
Pray for Dawn
5.
Wait for Dusk
7.
Burn the Night