When you start to suspect your partner is betraying you, take care not to look paranoid. You need to analyze the situation before making any possibly untrue allegations.
It is difficult to be sure if they are betraying you, but be vigilant and at the same time, be careful not to be ruled by anxiety. Unnecessary paranoia will simply drive your partner away.
Here are some signs that he's probably betraying you:
1. Has started wanting less sex.
2. When the phone rings or a message arrives it jumps out of place and is not quiet.
3. Blush or start talking endlessly about a person you haven't known for a long time.
4. There is a distance between you, not just the physical.
5. It starts to disappear suddenly, it doesn't tell you where it is. It just tells you I was at work, at a meeting and so on! No more explanation.
6. If he has betrayed you before and you have forgiven him, chances are he will betray you again.
7. You feel it
Source: Marie Claire