An option that will take a lot of sacrifice from your wife:

No sex. Other than solo of course.

The up-side:
You won't be having sex with her while thinking about someone else.

The downside:
Both of you will not have a subset of your marital needs met.

The question for both of you:
Is that sacrifice too much?

You wouldn't be the first couple in history who loved each other but who abstained from sex indefinitely.

As Aarons_Secret said:
Concentrate instead on serving Him first.

If both of you do that, it will make it much easier for both of you to abstain.