Debbi Wood, 42, is so paranoid that her partner Steve Wood, 30, will cheat that she checks his phone, email accounts and bank statements several times a day for any evidence of infidelity.
And it doesn't stop there either as Steve - who started dating Debbi in 2011 - is even banned from watching women on television, or looking at pictures of them in magazines.
Doctors have now diagnosed Debbi with Othello Syndrome, a psychiatric disorder which causes sufferers to believe their partners have been unfaithful - even without evidence.