First off buying a strap on is a big jump and too aggressive, if you sit down with her and say maybe we try a few smaller butt plugs and if it's OK after that then proceed forward. You should be willing to at least try once to make her happy and to see if you would truly like it. And if you show her you tried but didn't like it that speaks in volumes. But I say try small steps before going all full strap on and if she continues the aggressive nature to move forward without you agreeing then you need to look at stepping away from this relationship. Relationships are about compromise. Meeting halfway, we all have sexual desires and fantasies we want fulfilled but not with hurting the other party.