A career girl convinced her instinctive man-picker is broken, creates a complicated love square when she discovers the sequence that triggers love and lust in the brain, and uses it to transfer her infatuation with an unavailable co-worker to her “just friends” bestie.

Not sure if this is better but here goes:
-----
"Tired of picking Mr. wrong; a love-shy behavior scientist creates a behavior love drug that shocks her every time she falls for an asshole" :)
-----
Pavlov's love dog.

I'm not sure I see a love square (MC + co-worker + bestie makes three).

Also what is the MC's goal: turn lust into love?

What's at stake: lose a bestie, gain a lover?

I hear the opening to Peter Gabriel's, Games without Frontiers:

"Hans plays with Lotte, Lotte plays with Jane
Jane plays with Willi, Willi is happy again"

Hope that helps.

And why wouldn't she use her discovery on the unavailable guy to get him to fall for her?