If you constantly call or text him even when he isn’t replying he might not be that into you anymore. One of the biggest signs he’s losing interest is he's not longer making an effort to contact you. He may have lost interest chatting with you or he could be talking to someone else, either way it's not a good sign.
People get busy and schedules don't always mesh but if your guy is intentionally avoiding making plans then he might be losing interest. If he doesn't include you when talking about future plans that is a sure sign that things are going downhill and you should change something or call it quits now.
Affection is an expression of care that symbolizes security, protection, comfort and approval. It's a vital ingredient in any relationship. If he's no longer trying to hold your hand or make advances towards you then this might be a sign that he's losing interest.