Does your relationship have a swag gap, and is that always a bad thing?

Ifesinachi Mamah couldn't date someone who didn't put effort into their appearance.

"I would just want us to both look good," says the 23-year-old from east London. "If you see two people together, you want your overall vibe to match, or at least flow cohesively."

Couples with an obvious style difference are being described on TikTok as having "swag gap" relationships. One partner might be less fashionable - or appear not to make as much of an effort with how they look.

One of the most prominent examples is the contrast between Justin Bieber and his wife Hailey, pictured during an event for her beauty brand.

He wore a grey tracksuit paired with yellow Crocs and a pink cap. She rocked up in a chic red mini-dress with matching shoes and bag.

Newly-married couple Selena Gomez and Benny Blanco are often described as having a swag gap, too.

In TikTok videos, people have lamented past relationships they've described as having swag gaps, or, like Ifesinachi, said they could never bring themselves to be in one.

She describes a swag gap as being when "two people in a relationship don't see eye-to-eye in terms of aesthetics, clothing and maybe lifestyle". One partner is more into fashion and always makes an effort to present well, while the other "doesn't care about how they look".

This can have wider implications for a couple beyond just looking mismatched in public, Ifesinachi says. Perhaps the person who makes less effort with their appearance "doesn't care about what restaurant they're going to or what kind of dates they plan", she says.

Dating coach Vicki Pavitt suggests swag gaps might lead to conflicts as partners want to feel "proud standing beside each other". If one isn't putting as much effort in, "it can feel like they're disrespecting the relationship", she says.

But it could just be that they're simply not as fashion-conscious - despite their best intentions.

Relationship psychologist Anjula Mutanda says: "Your partner may have made a lot of effort, but in your mind, they don't quite stack up to your high standard."

If the more stylish partner sees themselves as superior because of the way they look, and "weaponises" their sense of style, this could lead to an unhealthy power dynamic, she continues.

And trying to influence the way your partner dresses - buying them clothes, telling them their outfit doesn't work, or suggesting a wardrobe clear-out - is fraught with risk.

"You want your partner to be a reflection of you in some way," says Vicki. "I think that's really natural."

But trying to mould someone's appearance according to your preferences is dangerous, she argues, as the person on the receiving end could see it as an unwelcome imposition.

Instead, you should be "uplifting and encouraging", says relationships coach Persia Lawson. If you're gifting your partner clothes, for example, make sure they are things they'll actually like and wear, she says.

Jessica Raialo, a 25-year-old from New Jersey, says she has a swag gap in her relationship - but insists that doesn't need to be negative.

She and her boyfriend's styles "couldn't be any more different". Hers is maximalist, hippy and eclectic, while her boyfriend dresses like a "typical skater in his 20s", in vintage band T-shirts and Vans in various shades of grey.

Jessica, who is wearing cheetah-print leggings, an orange-fringed cardigan and long green feather earrings as she video calls the BBC, says her boyfriend still puts effort in and "always looks great".

She sees style as a spectrum rather than a hierarchy of good and bad. "I feel like there's really cool stuff in everything that everybody wears," she says.

Jessica would never try change her partner's style, she says. "If you're trying to change your partner like that, you're probably with the wrong person."

For many, swag gaps go far beyond appearance and fashion - and instead encompass differences in success, fame, confidence "or just energetic aura in general".

The issue with a swag gap, according to TikToker Isabella Duffy, is if the partner with less swag feels left behind or insecure. That can cause jealousy and resentment, she suggests.

She's experienced this disconnect herself, she says, as a social media content creator. Partners were unable to handle the "attention, praise or just interesting opportunities" that would come her way.

Being a female breadwinner can cause this swag gap too, Isabella adds.

"The only way the swag gap wouldn't be problematic was if the partner with less swag was a cheerleader for their partner and proud of them rather than emasculated or resentful."

Ultimately, she is convinced that the key to a happy relationship is to have the same level of swag - to be on the "same energy plane and see each other as co-conspirers rather than competitors".