I guess it depends on whether lying is acceptable to you personally (and to both of you as a couple). For us, it's deal-breaker. We can both deal with anger and arguing better than we can deal with dishonesty. We'd rather just "have it out" and be done with it. And really, it makes the relationship so much more comfortable, because we never have to second-guess one another. What we say is what we mean, so we're able to trust, relax and let down our guards with one another.