Picture the scene: you arrive home early one evening after work, slide the key into your front door and hear a distant banging and moaning coming from your bedroom. Rushing in you find your partner under the bed sheets, entwined with another person. Now imagine how you would respond if the other person was not a human being at all, but a sex robot designed to fulfil your partner's every desire.

Thanks to the rise of sex robots and technology that makes them appear increasingly realistic in their appearance and personalities, walking in on your partner having sex with an android is no longer beyond the realms of possibility. And while sex robots currently cost thousands of pounds, "brothels" stocked with the devices have already popped up in countries including Germany and France.

But does having sex with a robot really count as cheating? A sampling of over 5,000 US singles surveyed by Match.com found that while one in four respondents would hook up with a robot, half would consider it cheating if a potential future partner used one.

I posed the question in an admittedly unscientific straw poll to 31 people on Twitter. It showed that 26% would consider it cheating if their partner used a sex robot; 13% wouldn't care; and 61% wouldn't consider it cheating but would be "weirded out".

The question seems to come down to the fact that sex dolls aren't sentient beings. A sex robot can't rival a partner's emotional connection [one would hope]. Some might argue sex robots are nothing more than highly advanced vibrators. On the other hand, the idea of a partner gaining sexual gratification from an immobile android designed solely to cater to their fantasies without needing to gain consent might be daunting or off-putting.

"I'm not sure I'd consider it cheating per say, but I'd consider it reducing women to inanimate sex objects and that would be a dumping offence for me!" commented one friend when I posed the question on Facebook. "I think I'd rather she slept with a human!" said another.

What complicates the issue further is that the definition of cheating is a fluid one, Denise Knowles, a counsellor for the relationships charity Relate, told IBTimes UK.

"Relate's research has found there's very little agreement around what actually counts as cheating and this can cause a lot of tension in relationships," she said.

Perhaps a better approach to the question is considering why we cheat at all and where sex robots fall into this narrative.

Research shows that we cheat for a variety of reasons, from sexual and relational issues, to simply seizing an opportunity which presents itself despite not being dissatisfied, according to Alicia Walker, assistant professor of sociology at Missouri State University, and author of The Secret Life of the Cheating Wife: Power, Pragmatism, and Pleasure in Women's Infidelity.

"In terms of cheating with a sex robot, the appeal would have to include the promise of not being disappointed," she argued. "The robot isn't going to reject you, declare itself not in the mood, or critique your performance. Additionally, it's a coupling where you do not have to be concerned with your partner's pleasure or needs."

However, her study into women who used an infidelity dating website showed that they sought other partners because they were in sexless or orgasmless marriages. "After years of wandering in a sexual desert, they decided they either had to break up their families or get their sexual needs met," she said. "So, they were cheating to stay."

"Many people do believe that if a sex toy is introduced into sex play it is an indication that you aren't a good enough lover, but that is a misconception," she added.

"Other people have concerns that a sex toy could replace them, or that their partner will require the toy to orgasm, or even to get sexually aroused. Research has found that men who report using vibrators regularly on their partners actually score higher on measures such as sexual desire, satisfaction, and erectile and orgasm function.

"Overall, the data shows that when a couple can sexually explore together they report an ability to maintain desire and passion for one another. And some research has shown that when couples report satisfaction with their relationship they are more likely to also report the use of sex toys together.

She added: "Sex toys can increase sexual satisfaction. Another way to look at it is this: your partner must have a lot of trust in you and the level of communication in the relationship to even broach the topic."

So do sex robots present an existential threat to monogamy, or is it an age-old problem of feeling inadequate and questioning trust in a relationship presenting itself in a modern way?

"There have always been ways to be unfaithful, such as seeing a sex worker or having a physical affair," said Knowles. "It's just that now, largely because of technology, there are potentially more ways that you could betray your partner. The principle remains the same though – if you're doing it in secret and you know your partner wouldn't be happy with it, it's worth thinking twice about it."

"The worry someone may feel has everything to do with the negotiated boundaries in their relationship, as well as the level of trust, communication, and intimacy the couple enjoy," chimed Walker.

"We'd encourage couples to discuss boundaries early on in the relationship and to keep revisiting the topic to make sure they're still on the same page," advised Knowles. And that conversation might now need to cover sex toys, and robots, too.