I expect men to be faithful. I also don't see how this is at variance with platonic friendships between genders. I am a Christian and have a close Christian male friend who is like a brother.

I have never cheated and I have never had a man cheat on me. But I vet people and take my time before I trust.

My fiance has a couple of close female friends just like I have a couple of close male friends. We trust each other so it's not an issue.

It used to be easier to have friends of different genders because groups of friends did things together. Or there were several children in a family, so boys got to know their sisters, cousins, sister's friends, etc., and relate to them as people who were to be treated respectfully. If someone cheated - everyone in the group would know, which encouraged people not to do it.

In some cultures, this still happens. For example, I have Spanish and Hungarian and German friends who have friendships with the opposite sex but never cheat.