If you find out your partner has been cheating on you, it can feel like your whole world has collapsed. 

Yet if you’ve been in a relationship for a long time, you too might be attracted to someone else, even though you still love your partner. So, how to deal with cheating? There are no straight answers, but we run through the issues in our Top Five Facts number 18.

“Marriages are made in heaven but tested on Earth,” a friend of mine commented.

She was referring to her own bad marriage. “It’s been downhill since the beginning. Don’t blame me for having an affair,” she said. I played the mute listener as she continued: “My marriage is a failure, but ending it is difficult. So I stay on and look elsewhere for happiness.” 

Cheating sets couples on the road to divorce, a recent study found.

In a marriage, cheating is usually a deal breaker. Yet 34 percent of men and 19 percent of women in the USA say they’ve been unfaithful to their spouses at some point. Mostly it’s because they’re unhappy with the relationship, bored with the sex or want more of it, or fall in love with someone else.

There are these people called evolutionary psychologists who have deciphered great excuses for male adulterers, I read this week.

Men can blame all the shenanigans on our genetic makeup. Apparently our brains are wired to procreate as much as we can. Hence we keep seeking out fertile young wombs. Remember ladies, it's for our species, not our penis.

A friend of mine told me that she was guilty of “emotional cheating”.

What does that mean, I asked her. “I’m not cheating in the real sense of the word. There’s no sex involved, but I feel very close to this other guy at an emotional level,” she said. That was a tough situation to be in, I thought. So, what’s she going to do about it?

Cheaters are more likely to have unsafe sex than people who have agreed to have an open sexual relationship, a recent US study found.

They’re less likely to use condoms, either with their partner or their lovers. Is it because cheaters are just risky types anyway? Or do they like kidding themselves they were swept away in the heat of the moment?

Q: I’m very jealous of my boyfriend’s best girl friend. I’m not sure if they’re ‘just friends’.

He hugs and kisses her more than he would do me. I've been with him about 10 months now. I love him so much. I always knew he had a lot of female friends. I didn’t think I’d get possessive, but now I am. What should I do? Seerat, Jaipur

Q: I watch a lot of pornography and almost on a daily basis. I also indulge in online sex. Am I cheating?

I have never met my cybersex partner and I don’t wish to. But I like the online sexual relationship I share with her. Does this mean I’m being unfaithful to my wife? Santosh, Varanasi

“Monogamy is an utter failure," says US sociologist Eric Anderson. “The amount of cheating and infidelity is extreme.” 

His studies on the reasons people cheat show that the vast majority of people are unfaithful. Whatever we might like to think, monogamous relationships just don’t work, he says. 

“Dirty talk online or even cybersex is nowhere close to real-life flirtation and sex,” says Ankita from Mumbai, “so honestly I don't get this big fuss about infidelity online.”

She's been in a relationship for the past two years. “If a fun online life can make up for the excitement that goes away in a long-term relationship, then there’s nothing wrong with it.”