I have personally been in a relationship where my now ex-boyfriend has been unfaithful to me. I was in a denial but all signs pointing to his infidelity were obvious. When I was finally confronted with the truth, it broke my heart. He was my first love. It was not easy to accept the truth and end the relationship but I was glad that I did it.
I have certainly learnt from the experience and I can even proclaim that I have since become the expert in sniffing out a cheating boyfriend!
Below, I have listed out the tell-tale signs of a cheating boyfriend, based on my personal experience.

He needs his privacy when answering his mobile phone
His mobile phone rings. He instinctively walks out of the room. Or the house. The conversations are usually quiet and short but when he comes back in, he usually looks flustered. His mood probably changes after the phone call. Perhaps edgier, more nervous and he cannot wait to be on his own! His mobile phone is like his lifeline. It is always with him, even when he goes to the bathroom. Something is not right or natural, is it? He never lets you get anywhere near his mobile phone. You are not allowed to touch it. It is his sacred item.

He has very vague travel plans
He is away but you are not too sure where he is or where he stays. His whereabouts are always a mystery to you. It is never convenient for him to provide you the hotel where he is staying or the restaurant where he is meeting his clients. When you contact him, his mobile phone will most of the time be switched off or it will go unanswered or it will go dead after the first ringing tone. If he is a world traveler, he is probably also very protective of his passport from being seen by you. He cannot afford the risk of you flipping through his passport pages only to find that all the pages are blank and un-stamped, when he claims he has gone to Paris or Shanghai or Copenhagen or Mumbai for his business trips. Something for you to ponder on.

You are his phantom-girlfriend
You have never been introduced to his family and friends. His family and friends know nothing about your existence. Or if they do, they only know your name but do not know you are his girlfriend. Basically, you are the phantom girlfriend. So, the question you need to ask yourself is – why are you kept phantom? Surely if he has nothing to hide, then he should be proud of YOU as his girlfriend and make it known to his family and friends. Besides, if neither of you is a public figure or a celebrity, it is strange to think there is any need for you to be hidden away from anyone, particularly his close ones.

He wants you to play by his rules
He dictates when you should call him. He dictates when you should meet. He dictates where to go when dating. Basically, he controls everything. There is something fishy here. You have to ask yourself why does he have to make all the decisions and choices? There must be a reason for that. Is he trying to play a balancing act by guarding his actions, to avoid being caught red-handed or in any uncompromising situations?
He has to decide where to go on the Friday night out with you because he cannot risk bumping into ‘the other woman’, or ‘women’ for that matter? When you are always playing by his rules, not only are you dating a control freak, you are probably dating a cheater as well. So, you are forewarned.

Follow your natural female intuition
The minute you start having any nagging feelings about his behaviour, that is the first sign of red alert. There must be a reason for you to become suspicious of him, especially when all the above tell-tale signs become too obvious to ignore. You are a smart woman. If you feel that you must find the evidence to support your suspicions, then do it. Do not continue to accept his excuses and live by his rules blindly. It is time you make a wise decision for yourself.