Koeman has never brought up kisses, but it's clear that he's just as close to Memphis, who has probably played the best football of his international career under the former Barcelona boss, who not only brought him to Camp Nou but also made him the focal point of his attack during both of his stints in charge of the Netherlands.
Consequently, even though Memphis has come in for criticism for his inconsistent performances in Germany this summer, Koeman has always steadfastly supported the forward, who still divides opinion in his native Netherlands, where his association with - and continual support of - the likes of Quincy Promes, Dani Alves and Benjamin Mendy has not gone over well at all.
There is nothing remotely orthodox about Memphis, a religious rapper with his own clothing line. He is, at times, an incredibly contradictory character and his alleged arrogance has alienated some of his compatriots.
Indeed, there's a feeling that the second-most prolific player in the history of the Netherlands national team (46 goals) has done very little in major tournaments to justify his self-confidence, which is why he is not as revered as Dutch legend Ruud Gullit, another outgoing individual who both played the game and lived his life with a swagger - but also delivered in the biggest games on the grandest stages.
Wednesday's semi-final against England, thus, feels like a defining moment for Memphis. He was heavily criticised for his performances in his country's first two games, against Poland and France, with many calling for Wout Weghorst to start up top instead.
But even if the latter is tasked with leading the line in Dortmund, it remains highly likely that Koeman will still start a player that ranked second for pressures applied in the final third in the group stage, got off the mark at the Euros with a well-taken goal against Austria, created more chances than any other player on the pitch in the last-16 rout of Romania (five), and also contributed a crucial assist from out wide in the come-from-behind win over Turkey in the quarter-finals.
"He's a very good player," Koeman said. "Of course he can play better, but I want to make it clear that he plays an important role in this team. This team needs him and he needs the team."
That's certainly true of the showdown in Dortmund. This is a glorious opportunity for Memphis to change the negative narrative; to belatedly show the football world that there's much, much more to the Netherlands enigma than fancy cars, cowboy hats and controversy.