Agreed with poster before me. Given your age, I'd say mid-life crisis. I'm much younger, but my appearance changes styles about every year or so, I'd say it's pretty normal. Is he staying late to work? Going out on important errands or business trips? If not, I'd say everything is fine and he's just finding a new change of pace.
I agree with the Guys. Either a mid-life crisis or he's trying to look good for you. I highly doubt he's cheating and I wouldn't look too hard for lipstick around the collar because that screams distrust.
OR He saw part of the South Park Episode where all the men go metrosexual. On a lighter note (: