Mr Veritas, Incapacity Benefit is NOT means tested, so it matters not a jot how much your partner is earning.
You can get Incapacity Benefit even if you are also in receipt of a private pension (if you are under state retirement age) although it can affect the amount you actually get.
I don't understand why your IB was affected by your partner's income - it should not have been.
http://www.direct.gov.uk/en/DisabledPeople/Fin ancialSupport/DG_10016082
"What is it?
Incapacity Benefit is a benefit that you can claim for if you are suffering from short or long-term ill health. It is not means tested, but in most cases it will depend on your record of National Insurance contributions."
http://www.askcab.co.uk/money_site/mINCA.asp
The DWP do like to know the ins and outs of everything about the claimant, and the immediate family, but partner's income definitely does not affect a person's claim for IB.