Intimacy is no longer exciting
Trying new things in a relationship basically keeps the relationship strong. If the person is having a habit of trying new things, and if your relationship is going nowhere in keeping it exciting. Then he/she might be having fun with someone else keeping the intimacy strong.

He/she might find getting bored around you
Pay close attention to the signs, when you find your partner is finding it difficult to keep the conversation going. Or he/she might be bored also with the normal conversation. Spending time is must but if that borders one even for a single second, then this one is sure signs.

And are less likely to communicate
Excuses and lies are fine for sometimes, but basically it will ruin your relationship in a long run. So if the person is finding it difficult to communicate with you and are bothering you with their truthful lies then this one is a sure sign.

He/she always get carried with their late excuses
Late comers never find a perfect place even in a good company, so if the timing is constant than it will probably be the main factor in breaking the relatonship.

You will definitely find more problem with their openness
Probably, more secrets comes with more openness. And if you find it suspicious while checking or going through their devices with no glitch then there might be possibly something fishy which has been kept under the mat or been deleted.

You are even unaware about their new found close friend
You might have met all of their fellow friends, but sometimes, a smile or an intuition can tell all. You might be not aware about their new friends, but they are real secrets who are hidden even with the closed one.

Even started spending less time with family
If he/she might be giving or spending less time with their beloved then there might possible signs, that they are having a secret besides their family. Because people will do anything to spend some quality time with love ones nor avoid them.

They started to become distant
Long distance is predicted but living under the same roof and even finding it difficult to even spend some time then these are sure signs. You will find that your partner is distancing themselves from every corner of your conversation, and that distance is playing key role in sudden departure.

They started picking up new habits
People tend to get attracted towards behaviourial of opposite person whom they find it attractive. And if that is certain then you would probably surviving in a wrong relationship.

When you find it suspicious things around them
They better don't share things with someone else. Because if the same things they like doing or sharing with you are also doing the same with others. So better than being suspicious rather blurt it out or go for sure signs to find out the truth. These are probably one of the signs that he/she might be cheating on you.