His matchmaking service, which has just gone online, has met criticism on opposing fronts. Orthodox Jewish rabbis say Harel should be doing more to encourage gays and lesbians to try to change their sexual orientation. Liberal religious gay groups see Harel's approach as a ploy to suppress homosexuality.
The matchmaking presents an array of challenges. The relationship may be loveless. The partners may be tempted to seek sexual satisfaction outside the marriage. And the couple may need assistance to get pregnant. But Harel insists he just wants to help people have children, an important commandment of Jewish law.
"The main aspiration here is parenthood," said Harel, 36, from his home in the Jewish West Bank settlement of Shilo. "It allows them to become parents in a way that is permitted by religious Jewish law and prevents a conflict between their religious world and their sexual world."
Most rabbis encourage gays to suppress their attractions, abstain from gay sex or undergo therapy to try to go straight. Harel believes some gays can alter their sexual orientation through therapy, and insists many do. The American Psychological Association has declared no solid evidence exists that such change is likely.
Harel said his method is meant for those who can't change, yet want to remain observant and have children.
Harel began matching lesbians and gay men six years ago, he said, because he recognized a "deep distress" among people "facing a dead end road."
More recently, Kamoha, a religious gay group, began receiving inquiries from gay men and lesbian women about this approach. Kamoha linked up with Harel and last month began publicizing the initiative on its Web site.
Harel says he has wed 12 couples, and several have had children. More than 80 people expressed interest in the matchmaking service when it was publicized by word-of-mouth, and since it went online two weeks ago, Harel says he has received dozens of emails.
"Rabbi Harel introduced us and there was a good initial click," wrote Sari and Avi, a couple Harel set up, in a testimonial on Kamoha's site. "It's not love. It's chemistry, a sense of understanding and partnership, trust and appreciation."
Harel was unable to persuade the couples he has already wed to speak to the media. But Kamoha referred The Associated Press to a man who has applied for Harel's services, a 35-year-old Orthodox Jew in the closet.
He has had casual sex with men but desperately wants to raise a family. He said he has dated numerous straight women; none of the relationships led to marriage.
"It is a risky experiment but there is no other choice," said the man, who refused to give his name because he is hiding his sexual identity.
He said he was willing to forgo love if it means being able to have children. He wants to try to refrain from seeing men when he is married but would discuss the issue with his wife if that changed, he said.
Harel said as long as both parties are aware the other is dating, it would not be adultery in such a union. He said the same would not be true for a straight couple because they are sexually compatible and have no reason to look elsewhere. Jewish law forbids adultery.
Harel contends that gay and lesbian partners learn to love each other once children arrive. "Their love is based on parenthood. Parenthood is the glue and it's strong."
Harel leaves it to the couple's discretion whether to divulge their sexual identities to their children but he recommends they consult with a professional first.
Potential candidates email Harel, who meets with them to assess if they are emotionally ready to be fixed up. Harel then picks a suitable match and introduces the parties. They are put in touch with therapists who are to assist them in their new life. Once they are married, they each pay around $400 for Harel's service.
Israel's secular majority has largely embraced the Western gay rights movement that has led to six cities, among them New York, legalizing same-sex marriage.
There is no gay marriage in Israel primarily because there is no civil marriage and all weddings must be done through the Jewish rabbinate, which does not marry gays and considers homosexuality a sin and a violation of Jewish law.
Gay adoption is officially illegal but some couples get around the law and surrogacy is an option for many same-sex couples. The partner of a parent can adopt the child of his or her partner. There are campaigns to allow for civil marriage which could eventually pave the way for legalizing gay marriage but Israel is far from both.
Still, Tel Aviv is considered one of the most gay-friendly cities in the world, with annual pride parades filling streets and rocking into late hours.
Among Orthodox Jews, homosexuality generally is considered an abomination. Gay observant Jews may be ostracized by their families and many opt to hide their sexual orientation. Only the more liberal streams of Judaism embrace gay couples and even gay rabbis.
In recent years, a number of religious gay groups have emerged, joining pride parades and demanding to be accepted while not going so far as to ask for religious recognition for their relationships.
The liberal religious gay group Havruta opposes Harel's approach, saying it seeks to "erase" homosexuals from the Orthodox community.
"They are saying, 'Changing them isn't possible, but how else can we hide their existence? If we can't fix them then let's set them up with lesbians,'" said the group's spokesman, Daniel Jonas.
Yonatan Gher, the head of the Jerusalem Open House, a gay community center and advocacy group, said he doesn't judge the lifestyle choice Harel advocates, but hopes young religious homosexuals don't feel pressured into choosing it.
Rabbis have criticized Harel's method because it doesn't try to discourage gays and lesbians from seeking to change their sexual orientation.
"There is an alternative," said Rabbi Shlomo Aviner, from the Jewish West Bank settlement of Beit El. "When people hear voices that say you won't succeed (to change), they think, 'Why bother trying?'"