Hi James,
I disagree its not your policy, you may pay the premiums but its taken out against the life of your ex-partner. Why wouldn't she want money against her life paid to a beneficiary of her choosing. I can see you are going to be difficult to convince here....... If I took a life insurance policy out on my neighbour, well could I do that no. You were only able to take out the policy with your ex's consent, so surely it makes sense that you should only be able to maintain it with her consent.
I would be very nervous if an ex had a policy out on me. Someone that is no longer emotionally vested in my life but would profit from my death........