Sienna Miller sparked discussion during her appearance at Wimbledon over the weekend – and it had nothing to do with the stylish, off-shoulder white dress she was wearing.
The actress, 40, was spotted kissing new boyfriend, 25-year-old actor Oli Green, who she has been dating for several months.
So far so normal – except that also sitting court-side, in the seats directly behind them, were her ex-fiancé actor Tom Sturridge, 36, and his partner, presenter Alexa Chung, 38.
Miller and Sturridge, who spilt in 2015 after four years together, are co-parents to their nine-year-old daughter Marlowe.
In 2017, the actress told Harper's Bazaar that their break-up wasn't "acrimonious" and that they "still love each other".
Indeed, the pair seemed to be on friendly terms, with the two sets of couples at one point seen happily posing for a selfie together.
However, the cosy dynamic will have been a surprising sight to those who struggle to remain in the same room as an ex partner, let alone go on a day out with them and their other half.
What's more, relationship experts believe that there could be more to Miller and Sturridge's respective kisses than might at first be apparent.
Referring to Miller's thought process specifically, psychologist and psychotherapist Nova Cobban notes that it "may well have involved wanting to let others know that she’s happy, that her relationship has passion and she is loved.
"It becomes important in front of an ex to communicate having moved on and being successful in finding a new relationship.
"It’s also possible that she would want her new boyfriend to feel secure with her ex around, and a kiss is often a way to reassure or to connect in a moment of uncertainty."
Of course, Miller's PDA may have had nothing to do with the presence of her ex: quite likely she was simply caught up in the moment of being with her current partner.
"It can often be that we seek to say with our body language something that we wouldn’t verbalise," says Cobban.
"We want to feel like the old relationship does not have a hold on us and we often want to show this publicly – whether that’s true or not – that we are happy and in a great new relationship."
But what about the etiquette that comes with kissing a new partner in front of your ex? Jessica Alderson, relationship expert and co-founder of So Syncd, believes that it depends on the individual scenario.
She explains: "It comes down to whether you are both over the break-up.
"If you think there's a chance that they might still like you, it's best to avoid kissing your new partner in front of your ex – it's important to show them empathy and respect.
"A good way to think about situations like this is how you would feel if you were in that person's shoes. If you are both completely over each other, then it's fine and essentially no different from kissing your other half in front of a friend."
However, Alderson insists that you shouldn't rush into openly being intimate with a new partner – even though it might momentarily feel empowering.
She warns: "If you had a bad break-up – say your ex cheated on you or they broke up with you out of nowhere – kissing a new partner in front of an ex can temporarily make you feel good.
"However, this feeling will be coming from a place of resentment rather than true confidence. Even though it might make you feel good in the moment, this feeling won't last.
"Long-term, it's much better to focus on yourself and your own happiness rather than on your ex."