From the comfort of their homes and with just a few clicks of a mouse, virtual universe residents can do just about anything they want.
Second Life, an online world that lets users navigate through a digital planet, has a functioning economy with its own currency, an array of employment opportunities and a bustling social scene, nightclubs included.
And, for those looking for virtual intimacy, residents of Second Life can connect with other users, known as "avatars."
The universe, which has a population of more than 8 million, has seen approximately 35,796 of its residents engage in partnerships, according to Linden Lab, the developer of Second Life. Partnerships are akin to marriage and participants indicate these on avatar user profiles.
Sometimes these online unions, marked by instant message communication and even virtual sex, lead to real-life phone talk, meetings and all the activities that may ensue from that.
Virtual Love Turns Real
For Heart, a 37-year-old woman on Second Life who asked to use her avatar's name, a relationship that began in the virtual world is now part of her real life. Her two-year online relationship led to in-person meetings and eventually a real-world partnership.
Second Life led to troubles in the relationship with her boyfriend at the time, Heart told ABC News. Heart said she eventually left her boyfriend for her Second Life partner.
"[Joe] filled all the gaps that were missing in my real-life relationships," said Heart. "My real-life boyfriend used to walk past the screen and see what was happening and I used to tell him it was no big deal and it was just a game. I felt guilty about it."
While Heart said that she and Joe had sex in Second Life, she said they found it more entertaining than sexually stimulating.
Even those who never meet their Second Life mates may encounter difficulties with their flesh-and-blood partners.
Last week, The Wall Street Journal published a story about Ric Hoogestraat, a Phoenix man whose wife, Sue, is growing tired of his continued interested in Second Life. Much to Sue's dismay, Hoogestraat's avatar had gone as far as marrying another avatar on Second Life.
It's "devastating" when her husband is too busy having sex in the virtual world to pay attention to her in the real one, Sue told the newspaper.
Does Virtual Cheating Count?
Couples similar to Heart and Joe are redefining the bounds of dating, marriage and infidelity.
For those relationship experts trying to make sense of it all, there's a growing debate over what constitutes cheating, online and off.
Technically speaking, any energy — emotional, physical or monetary — exerted outside of a person's primary relationship can be considered cheating, relationship experts told ABC News.
"Whether it's an emotional affair with no sexual contact, an e-mail relationship or a virtual-reality relationship, they're all different forms of the same phenomenon, which is channeling to someone outside of the relationship," said Susan Heitler, a clinical psychologist and author of "The Power of Two: Secrets to a Strong and Loving Marriage."
"It's cheating in the sense that it's forming relationships and fostering loving feelings or sexual feelings toward someone or something outside the appropriate partner," she said.
Virtual cheating may have the same sting as real-life cheating, too.
"The impact that they all have is that they are detracting from the primary relationship," said Heitler.
Watching pornography, masturbating and now becoming involved in virtual relationships are all activities that take a person's attention away from their primary relationship, one marriage expert told ABC News, but whether it's cheating depends on the degree to which someone does it.
"The same rules apply to this as say, pornography," said psychoanalyst Bethany Marshall. "It's the amount of energy that is devoted to the excitement away from the relationship."
"Some of the ways to determine if it's cheating is if you're investing more energy and excitement outside your relationship rather than in it and if your partners would disapprove and you're knowingly going behind their back," said Marshall. "It's a perversion if you're more in your fantasy life than your real one."
"Character fantasies are worse than porn because you're actually developing an attachment with another character, and if you keep returning to this person again and again then it's an ongoing relationship."
Real Questions in Virtual Worlds
Opinions about cheating in real versus online worlds abound and there's no consensus on what's right or wrong.
"Nobody is really sure how people perceive online relationships or when they are cheating," said Nick Lee, a recent doctoral graduate from Stanford who studies the psychologies of virtual environments like Second Life. "It's not clear to what extent chatting someone up online is a date or if it's OK if you have a real relationship."
"If you're role-playing relationship online and you don't want your spouse to find out, then there's probably something wrong," said Lee. "If you feel like it's something you want to hide, then that's a good litmus test."
Lee chalks up the popularity of relationships in virtual worlds to the feeling of invisibility a user enjoys knowing that his or her identity is unknown.
"Users say they feel like they really get to know the person by getting to know them in a virtual environment," said Lee. "In the physical world, if you have access to great makeup and stylish clothes [that] has a lot to do with how much money you have and what your social status is. The thing in Second Life is that you can buy that body with a click of the button."
Some Fantasy Is OK
Relationship experts say online worlds can be a good release for many people, but it's wise to set boundaries in programs like Second Life.
"In good mental health, you want the fantasy — whatever the fantasy is — to actually point you in a real relationship with a real person," Marshall told ABC News.
Cheating in the virtual world though is likely to continue to be a problem area for real-life relationships, said Marshall.
"More relationships are breaking apart because of [Internet] access," said Marshall. "People are going to have to interact and really be honest with their partners."