Is there a word for when a person's fear of something causes them to take a course of action that turns that fear into a reality?
Example: Someone who's afraid that the person they love will leave them and find another lover, smothers them with attention and shows their fear through jealousy. This motives their lover to leave and find someone new.

In the study of folklore, there is a tale type called the Patient Griselda where a jealous husband tests his wife's fidelity in a Job-like series of escalating torments. (The tale appears in the Decameron and the Clerk's Prologue in Chaucer's Canterbury Tales.) I don't know of a generic term for this sort of thing, though.

I don't know of a single word, but it sounds like a "self-fulfilling prophecy." Sort of like how the stock market works.

That's the expression that came to mind for me, too.

Another term for the dilemma might be "shooting oneself in the foot." It's also similar to the "Oedipus effect."

The word I always use is phobicautodidactictransfiguration
And when I use me special word I always get ovation.

When Dukes and maharajas
Pass the time of day with me
I say me special word and then
They ask me out to tea.

Um diddle diddle diddle um diddle ay
Um diddle diddle diddle um diddle ay!

This sounds anyway far less painfull then shooting yourself in the foot.
The little poem is a cure for any fear, unless you fear crumbling your coockies.

Your precociousness has me on my feet!

Supercalifragilisticexpialidocious!

Sure Hrdra, that's easy for you to say.

But can you rub your tummy while patting your head?

I do not know a single word for the situation howewver the result can be given in a word : divorce.

Another example would be someone allergic to bee-stings who flails away at the air any time a bee comes close by.

Perhaps Mother Hubberdism.

Bill- (Bow, wow,) Gannon-

I can invent one. How about "autophoboactualisation"?

Sounds to me as if it is a psychophysiological response or in other words the effects of "The Law of Attraction" upon one who is phobic thus causing Counterphobia ( The preference by a phobic for fearful situations.) to occur . As for an actual term which states or defines that which you are speaking of, I honestly have no knowledge of such a word.

Good luck in your search though.