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:
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"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" :)
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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?

Very helpful! Thanks Nir.

Not sure what "...instinctive man-picker..." is, is this her feminine instinct?
Or a known mechanism/technique in the world of your character?

Did she miss judge her infatuation initially and decide to transfer it to another person or was this by mistake? After transferring it did it become a problem for her if so in what way?

I think a problem with this logline is that it is not clear what type of person the main character is and what it is she wants.

MC - career girl, but what is her flaw, goal, obstacle and is there an antagonist?

Hope this helps.

I'm really confused here.
What's a man-picker?
So your MC has a machine that can make anyone fall in love with her? Or she uses the machine to pacifiy her feeling for a co-worker?
Could you give us a short synopsis? This seems like a complicated storyline.