I know EXACTLY why you started this thread.
I think it's something that we cannot comprehend because it's all in the mindset of a person. Maybe something happened to him/her earlier on in life, which explains why they are now much more heavily guarded and cannot easily trust anyone, including their own husbands. I guess for others, they have their own logic and reason, perhaps even excuses for their doubts. But it is beyond us to help them, because they are unwilling to help themselves. And no matter what we say to them, they will still choose to believe in their own reason. So unfortunately nothing much we can do. dont't be too upset.
I love my husband too and I trust him. I think a very important thing is to have open communication with one another, and constantly remind each other of your love and COMMITMENT to each other. Sometimes things fall apart because we have different expectations, and we dont't let each other know about it. So I think it's helpful to talk about things and not go to bed angry at each other.
I can already sense some people reading this thread and sniggering, perhaps in their own minds even thinking, "wait till your husband strays."