You say you're catching him in "little white lies"--what kind? Are they of the "who was that on the phone?" or "who was that you were talking to at the store?" or "what took you so long to get home from work today?"
You say he's not the "same affectionate person"--meaning what? Is your sex life suffering? Does he not do the little things he used to do for you, like bringing home dessert or bringing you a soda or brewing coffee? My ex stopped bringing home baguettes and cheese, and when I became partially bedbound, he would get offended when I'd ask for a cup of ice for my soda--something he would never do before. Worse, he'd go out of town on weekends when we didn't have visitation with his child, weekends that I was sick and getting sicker.
If it's eating you up inside, Luv, you must not allow those feelings to do that. Take control over those feelings and redirect them where they belong--at him. He may not be cheating, but the only way you'll know for sure is to confront him with your suspicions.