Why not just friends?

It's become apparent to me over the years that there's a lack of understanding in relationships between men and women. I'm not sure if it's a universal trait, or if life is really so ridiculous. But it's sad, altogether. There are guys I've been friends with in the apprenticeship who, once married, are no longer "allowed" to speak to me. Why? I'm not looking to bed them. One, particularly, had an issue with his wife: I sent him three or four text messages about an upcoming exam. Seriously, it was legitimate. In fact, when I send text messages I send them with the assumption that they'll be read by the world. It's safer to think that way. However, the following school night, I was told by this guy that his wife had cancelled the text messaging feature on his cell phone, because of my "inappropriate texts". Honestly, they went something like, "hey test next week incls plc info/diags pg 10-34 & tables"...nothing at all insidious. There isn't even anything that could have been percieved as suggestive.

On the other end of the spectrum are guys who make it clear they want to be more than just friends, despite the fact that I'm married (or that they, too, are married); once I decline the invitation I'm met with hostility. Why can't I just be friends with a guy without it being percieved as something it's not? In my line of work, a good 90% of my coworkers are men, at least. Right now, there are no women on my site except for me. I'd like to be friendly, polite. I'd like to carry on conversation. I'd like to be open. But sometimes it's made impossible for me. Granted, I take certain precautions: I make sure I'm not alone with a guy off-site. It just looks bad, and I don't need any help in spreading the rumours that already circle jobsites. But I despise the fact that it has to be made more complicated than it needs to be.

Men: keep your mind on your work and not on your libido. Women: don't be so overbearing that he's driven away. Simple.