Coroners and Justice Bill

I still do not understand why the defence should not be used successfully. Why does the Minister wish to deny to a jury the right to make an assessment as to whether the offence should be reduced from murder to manslaughter on the basis of provocation? In virtually every other area, it will be allowed to make that decision, but apparently not in the case of sexual infidelity. What has the Minister got into her head that is making her want to withdraw that historic right from a jury?