There is no reason why narrative has to be at odds with ontology - it is just that we look for ontology (by which I guess you mean something like a universal, dare I say absolute, reality, acount of things) within a narrative framework and we allow that narrative framework a much larger say in defining it.

So we could ask: What reasons does the narrative give for Jesus’ death and resurrection? How does the narrative explain its effects. We would have to talk about the various elements that went to make up Jesus sense of identity and calling, for example:

• reflection on scripture - and not least those texts that see the destiny of the many, as judgment and restoration, condensed into the experience of an individual;
• the preaching of John before him;
• the prophetic conviction that God was about to intervene decisively to judge and remake his people;
• observation of the historical condition Israel was in, knowledge of past conflicts between Israel and pagan overlords;
• his sense of vocation as a self-giving identification with Israel, derived from such events as his baptism, the testing in the wilderness, the transfiguration, Gethsemane, etc.;
• his own experience of life in intimate relation to, dependence upon, the Father;
• angry encounters with the leaders of Israel.

Do we still need a theory of the atonement to explain all this? Isn’t this the problem - that we don’t really trust the narrative, we don’t really trust the experience of those who followed him? We need an abstract theory - a quasi-scientific, pseudo-philosophical theory - to reassure us in a rationalist age that it all makes sense, that it’s all believable. But what is inferior about the narrative argument? Why “’only’ narratively necessary”? The logic of biblical narrative includes covenant and all its commitments, the struggle of the prophets with the failings of Israel and the purposes of God for his people, the experience of invasion and exile. These are all powerfully compelling driving forces that, to my mind, are more than adequate to ‘account for’ Jesus’ death and resurrection as a culmination of ‘narrative’ developments.

We can also begin to think quite concretely and historically about how Jesus opened up a new option for Israel, a narrow path leading to life. Whatever the hidden metaphysics of his death as an act of atonement, it created a community that sought to locate itself in that narrative of dying and coming to life. They were convinced that through this embodied ‘parable’ God had done something on behalf of Israel that required their participation. Only the whole narrative explains that.

If this all sounds too complicated, then we need to find new ways of simplifying the story - without falling back on heavily reductive appeals to a doctrine of substitutionary atonement, or some such, as though that made everything perfectly clear. Jesus retold Israel’s complex story through parables and drama, and I would suggest that we could also find more creative ways of communicating the ‘truth’ that lies at the heart of the narrative as we come to understand it better. Maybe we don’t really have the right sort of answers yet to your wife’s questions - maybe we need to find them.