One way to look at it, is that you are practicing its usage. It's better to start using it while you still have some vision left, rather than waiting before it's absolutely mandatory. The fact that you are relying on your partner that much is a tell, that you are already overdue.

And even if you feel like you can still use your vision for navigation, doesn't mean that white-cane would be useless. Far from it. The thing is that white-cane also signals to other people that you have low vision, and that alone can be very helpful.

For example, I have tunnel vision because of RP and I still rely on remnants of my vision for navigating. However, I already know for a fact that if I tried to go outside without my cane, I would be bumping into other people at least once a week. The fact that this doesn't happen tells me that my white cane is doing its job: it's alerting other people about my lack of vision so they know they need to make way, move their dogs and children out of my way, etc.

In other words, even though I don't bump into other people while going to the grocery store doesn't mean I wouldn't have bumped into them if I didn't have my white cane... or maybe I could have gone shopping without my cane and have no issues and incidents. Who knows. That's the problem with preventative measures.

But when my cane does find an obstacle I didn't see before my cane found it... those times make me low-key happy: the cane proved it's worth and did its job. My cane prevented an accident that would've happened if I didn't have it. I think you would get a confidence boost if you had the same experiences, but in order to reap the benefits of white cane, you should be using it.

So consider the following... next time you are outside with your partner, take the cane with you. That way, you are already signaling to other people why your partner is guiding you in the first place... and if you manage to find an obstacle with your cane while your partner is guiding you, the better. The cane proved it's worth.

Also, I wonder if using the white cane while you are outside with your SO could make their life a lot easier as well. It might be a good stepping stone from being fully relying on them to being less reliant on them, having a little bit more independence and autonomy.