Why is my guy friend being distant all of a sudden? Is it me?

Why is my guy friend being distant all of a sudden? Is it me?
Before I go on, I have NO romantic interest in this man, so please don't go off on a tangent saying that I am trying to get him, I wouldn't get with him. He is a great friend; Wouldn't make a great boyfriend for me though lol.
--Anyways, I've been great friends with this guy for years & we would text/talk often. He is married & has been married even before having met me. No, we are not having an affair, we are just friends. Never kissed, nothing.
Lately though, out of nowhere, he'll pulled away from me. He no longer talks to me on the regular basis like before & whenever I would reach out, he would be very cold/answered rarely & with only a few words.

We have had no fights, no issues around the time he started doing this. In fact, I feel like we left off at a very positive place.
His wife knows me & she likes me/respects me since I respect her & her daughter.
When I had asked why he hadn't been himself lately, he responded "Been trying to clean my life up a little right now."
I know it's not a financial issue.

There was even a point where we didn't communicate for almost 10 days.
--Now, we used to work together, so I visit my coworkers/ him weekly. This last week when visiting, he acted like nothing happened, making a few side comments about not having heard from me in a while.
The thing is, when we were alone having coffee that day, I asked him if everything was okay. He said yes. I even asked more than once & he said "everything is good" (I still felt like there was something there).
He at one point said, "I think I'm actually glad I didn't talk to you for a while, I hope you don't take offense to that." At another point when I asked him what's wrong, he said "I just have a lot on my chest."
I'm confused & a bit hurt--Does he not care for me anymore? Is he just bored?
I don't want to loose my friend.
Why is my guy friend being distant all of a sudden? Is it me?
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