It was Rakiatou Idi’s wedding night. She waited for her new husband on their new mattress in their new house while a joyful gang of young wedding guests filed in and out to take pictures of her on their phones.

As is the tradition in Niger, the bride wasn’t invited to the ceremony so when Mohammed Yaou’s friends delivered him to her, carrying a ceremonial cloth over his head, it was the first time she had seen her new husband all day.

A few months earlier Mohammed, a city boy, had come to their village on the green banks of the Niger river and asked her to marry him.

He brought with him some suitcases full of new clothes and shoes, and 300,000 CFA (£400) in cash – the brideprice.

“It was an unforgettable evening,” he said.

The couple’s friends and siblings made a photo montage of the couple and the gifts, posting it on social media.

“It’s to avoid any doubt,” Rakiatou said.

In some parts of the world, a couple announce their betrothal with an engagement-ring selfie on Facebook. Among the urbanites of Niger, a pile of suitcases and a wad of money have become the equivalent. On heart-themed backgrounds peppered with kiss emojis these montages now fill Facebook feeds and WhatsApp groups across Niger. And, according to Nigerien women’s activists, they heap pressure on young women to get married too soon.

Brideprice photos fill Samira Ousmane’s social media feeds. But the activist and founder of Nigerielles magazine lamented the fact that the money, formerly a secret between the couple and their immediate families and usually ranging between 50,000 and 15m CFA, has become something to show off about.

“It creates a desire when you see others posting these kinds of photos and it pushes you to accept men you don’t love or when you’re not ready,” Ousmane said. “You don’t know anything about the guy but, because you see everyone else posting pictures with a brideprice of 2m CFA, you want it too; you want to be married; you want to be called madame rather than mademoiselle.”

There is already a lot of pressure on girls to get married early: three-quarters of Nigerien girls marry before their 18th birthday, the highest rate of child marriage in the world. A girl’s education is usually over when she gets married and married life is often hard, with high levels of domestic abuse.

But technology is making it harder and is changing some aspects of dating and marriage.

Facebook has been used as a dating service in Niger for years. Nigerien women receive hundreds of friend requests and messages from men who “drag” Facebook trying to pick up women and girls.

Rabi Maikano met her husband on Facebook but the social network also nearly destroyed their relationship as after they were married he kept messaging other women, flirting with them and “liking” their pictures. They were on the verge of divorce but Maikano salvaged the situation by defriending her husband.

Divorce rates have soared because of social media, according to Niger’s most senior marabouts, or religious teachers. Every week they counsel unhappy couples and their number one piece of advice is for husband and wife not to have access to each other’s phones.

“Twenty years ago the number of divorces didn’t even reach the hundreds,” said Sheikh Djibril Karanta, sitting with three marabouts in white robes and gold watches in the Islamic association headquarters in the middle of a treeless clearing in Niamey.

Last year, by contrast, 820 couples got a divorce through the association. They lay the blame on Facebook and WhatsApp for making infidelity easy. “It’s not good. It’s against our religion. People are abandoning our culture for a foreign one and it’s all because of social media,” Karanta said, adding that women were more at fault than men. “Most of the time, the women are the problem. They watch TV series from abroad, and see how women earn money and are equal to men. But here in Niger men look after women and they are superior.”

Indeed, Nigerien women are getting ideas beyond their traditional station. For one thing many feel increasingly empowered to make their own relationship choices. However, some things are not changing: men can and often do have up to four wives.

Seven days after getting married Fati Boubacar’s “sister” – her husband’s senior wife – was making her life hell. The towering pile of pink suitcases from her brideprice picture were on top of the wardrobe but she was beginning to wonder whether she should repack them and if the 1m CFA (£1,350) brideprice she got was enough.

“The furniture I brought with me was worth more than that,” she said, struggling to keep the tears in. “Polygamy is so hard. She insults me all the time. I never expected this. Sometimes I even think about divorce.”

The solution, according to some male religious leaders, is for women to ditch social media. “A good wife shouldn’t use Facebook,” said Serge Abdul Razak, a young marabout (Muslim holy man) with his own television programme who recently put out a broadcast entitled How to choose a beautiful wife. “She should delete her account when she gets married and change her WhatsApp number.”

According to the marabouts, it is the wider changes that have given rise to the social media phenomenon that are really to blame.

People think they have the right to do everything now, they say.

Karanta added that 1,400 years ago the Prophet had written that there would be huge upheaval; this was it, he said. “We saw it coming.”

Omar Hama Saley contributed reporting