If you notice your spouse paying special attention to his/her appearance or changing his/her dressing habits all of a sudden, something is certainly fishy. Unless of course, they’re clearly doing it to impress you.
When it suddenly becomes a norm for your spouse to come late from work, there’s a chance he/she is straying. Try to question your partner in a subtle, casual way, without letting your suspicion show. In recurring cases, it helps to check with his/her colleague-friends.
If he/she chooses to spend weekends with friends over drinks rather than spend the night watching movies with you, try talking it over. Devoting less time to you is another signal that shows your partner is into someone else.
Twice as nice:
When they suddenly begin to treat you extremely well; it could be because he/she is on a guilt trip. Try to keep a tab on what they’re doing all day. Don’t be naive enough to buy their niceties as genuineness.
Aloofness: Your partner is definitely cheating on you if he/she demonstrates an unexplained aloofness or indifference in the relationship. Get to the bottom of it.