Recognize changes in his habits. A sudden shift in his grooming or dress can raise a red flag, especially if he appears to shower more often or has an unfamiliar scent. He might start staying late at work more often or claim he is spending more time with his friends. Although changes in habits don't necessarily mean that something is up, they indicate that something has changed in your man's life.

Watch out for strange and mysterious phone calls. If he is leaves the room to take call, whispers into the phone or refuses to tell you who is calling when you ask, he could be hiding something. Texting more often, checking the screen before answering or becoming nervous every time his phone goes off can signal that something is up.

Understand that your boyfriend can accuse you of cheating or acting suspiciously to deflect attention away from his behavior or project his guilt on you. Some cheating partners feel guilty, become stressed and then take out their feelings on their partner. Others think they are getting away with cheating and decide it's easy to cheat. When they think cheating is easy, they can become suspicious that you are cheating, too.

Confront him if you catch him in even a small lie about where he was or who he was with. People in relationships should be honest with each other. If he lies about small things, he will also lie about something bigger. Asking him why he felt the need to lie to you instead of telling the truth. Consider what causes you to respond angrily and determine if your actions inspire him to lie instead of speak the truth.

Communicate your concerns in a calm and emotion-free way. Don't be accusatory. Instead let him know how you feel and ask if you can talk about it. If he refuses to talk about your concerns, take that as a sign that he doesn't really care about your feelings. Don't try to force him to talk. If he doesn't want to communicate with you, walk away from the relationship or take a break for a while.