THAT WAS IT!!!!! Thank you for finding that.I think that the name of the movie is "A Very Long Engagement" (Un long dimanche de fiançailles in VF) with Audrey Tatou.
Temple of the Sea part 2? Sure, I'd like to see that.I'd like to see a sequel to movie 9 when they're visibly older. The sea temple's in trouble again (seemingly, anyway) so Manaphy sends a call out for Ash and May to come and help out. But it's all a clever guise orchestrated by the prince of the sea to bring his 'parents' together. Because he's so smart ;). And of course some trouble actually does happen and they have to save the temple once again. And then the two finally realize they're in love and get married at the temple! So romantic!<3
I can picture something such as weather problems like in the second movie. Stretch it out to be a bit outside just the temple, but still make it have something to do with the temple.
Although one thing I can't really see is marriage on what is effectively the first date. Maybe if they both admitted they had their feelings for each other bottle up for like 7 years, maybe that might work. But if they just realize it now then that's kinda pushing it.