Guy friend changed from hot to cold? Its confusing?

I have this guy friend I have know a few years. We use to have great conversations, hang out, he use to visit me on my job, text me all the time, call me frequently etc.

Well that has all changed, he rarely text, rarely calls, won't return my calls, we no longer hang out. I noticed even when he talks to me in person he gives me literally no eye contact (just brief) and turns while talking.

I continue to be a good friend as though nothing is wrong, but it bothers me. I noticed when he does text now he just text me to tell me where he is traveling to: Paris, Miami, etc. as to brag. The texts are at odd times (late evening or night) due to time difference.

When I just text or call just to say hello or see how he is doing, his text or responses are : Good or Well.

I feel friends don't do this to friends and we never had any disagreement or problems.

This guy went from hot (warm personality) to cold (stale).

So I thought of just ignoring him, no longer calling or texting, giving him his space-move on. If he text about his trips/vacations just ignoring it.

His behavior confuses me. If I ask him if he is ok or his behavior has changed, trust me he will say nothing is wrong. So I don't want to even go there.