You don't seem to have very much faith in human beings. Sexual attraction is not a weakness. As humans we have the ability to choose who we want as a mate or sexual partner. To go through ones life avoiding potential relationships with people of the oppsite sex because one is afraid one might sleep with them is completely ridiculous.
This is not a trust issue. Everyone trusts their spouse. Yet 40% of marriages will end with someone cheating, anyway. NONE of those people thought it would be that way for them. They all trusted that it wouldn't. They all claimed that they were strong enough to resist the temptation. Yet in the end so many of them didn't.
To be married, one HAS to trust their partner. Otherwise the marriage will be a living hell for both. But trust has little to do with outcomes. I may trust myself, and my spouse, and still end up ruining my marriage by cheating, or find myself having been cheated on. It happens all the time.
I think it's somewhat humorous that all the people on THIS thread are so certain that they nor their spouses will ever screw up in this area - an area of life notorious for humans screwing up. When the simple numbers dictate that many of you will sooner or later discover that you were wrong. You will screw up. And you or your spouse will cheat.
I'm not suggesting that we avoid friendships with the opposite sex because of the dangers involved in having them. I'm just saying that I think you all are being surprisingly naive about this, and that naivete will lead to an even greater risk of problems in this area for you. We humans are always lying to ourselves about who we think we are, and what we think we are capable of. And we add to the delusions by lying to ourselves about lying to ourselves.
Even a professional fire-handler will burn himself sooner or later, if he keeps handling that fire. My suggestion is that we stop pretending that we're immune to infidelity, and learn to live realistically with the danger. That means making realistic decisions about about the degree of danger we are willing to accept in our marriages, KNOWING THAT WE DON'T KNOW OURSELVES AND EACH OTHER AS WELL AS WE THINK WE DO.