Honestly, from reading your description I'm not quite sure what the focus of your story you'd most want to fit your title would be.
I personally like 7Sins as a good well-rounded title if you're willing to risk the confusion with the video game.
On the other hand, S.A.L.I.G.I.A. would be good if you want to play up the thriller/action aspects, but would be a bad fit if it's more romcom heavy than fast-paced.
a supernatural rom-com with hints of thriller/mystery and action. The mood of the story is a little depressing with some part of light comedy
Not sure from reading this part if you're shooting for a fun romcom or a more serious, dramatic tone. Sinful Behavior and Bound by Sin both feel like more risqué titles than you're likely going for, but I guess could work for a darker, dramatic romance. Hell's Bound would be good for a heavy romance, and Seven & Sin could go a couple ways depending on how the thumbnail looks.
Basically it depends a lot on what your primary focus and audience you'd like to grab for the story is.