Is it possible that one's own wife creates an "evil eye" or something of the sort, knowingly or unknowingly and ends up causing financial and health trouble? Is there any sort of "contract" couples can sign between themselves in which one can't harm the other's mazal etc? I ask out of literary curiosity only.
First you need to define what you mean by Evil Eye.
More to the point, the Talmud does mention that a wife's tears can have a tragic effect on the husband's well being.
E.g.: The Gemara in Kethuboth 62b cites the case of Rav Rechumi was arrived home late for his annual (Erev Yom Kippour) visit.
His wife got so worried that she started crying, and he was killed in an accident as a result.
כי הא דרב רחומי הוה שכיח קמיה דרבא במחוזא הוה רגיל דהוה אתי לביתיה כל מעלי יומא דכיפורי יומא חד משכתיה שמעתא הוה מסכיא דביתהו השתא אתי השתא אתי לא אתא חלש דעתה אחית דמעתא מעינה הוה יתיב באיגרא אפחית איגרא מתותיה ונח נפשיה
There are other places in the Talmud that cite poverty and other troubles as a result of not treating one's wife with utmost respect.
So, to answer your question: Make sure to always treat your wife with utmost respect, and then you won't have to worry about her feelings causing you harm.