I think, having read the OP three times that there add deeper issues here. Trust.

Essentially, what will you do to get what you want?

The separation of mileage collection and life is important, in much the same way that while all of us probably enjoy a series like Breaking Bad, it doesn't make us want to start making crystal meth. Reading Agatha Christie doesn't make you a murderer (or a detective!) and avidly collecting miles doesn't make you dishonest.

Has your SO benefited from your miles obsession or do they view it as stolen goods!?