My Take
I agree w all of the posts and thoughts here. Just some other ideas and theories of what will happen to him in hopes of making this a sweeter rather than a sadder ending. (warning spoilers) Honestly it was a delight just watching them have fun at the resort w the cheesy entertainment the gorgeous weather and idyllic background almost making a movie unto itself.
There are lots of references to his behavior and struggling condition already. A few to add I noted were his proclivity for the club lifestyle namely drinking, dancing, drug use and smoking featured prominently throughout.
He warns her of the harms of smoking knowing he is still under the addictive influence as he sneaks cigarettes at times. He tells her some drug use is ok if she wants to try it and admits he has done everything. His clock seems to be set to party hours as one scene shows he is still awake at 3:09 and they do a lot of sleeping during the day by the pool and on buses.
He admits to himself he is lucky to have made it to 30 and can't seem himself at 40. He can’t explain how he broke his wrist and what happened to his shoulder so drinking to passing out seems to be a regular event.
The karaoke scene is kind of pivotal. He refuses to join her then as a concession offers singing lessons. In here resent she says to ‘stop it’ as he knows he can’t ‘afford it’. Then he goes out and gets passed out drunk.
I think he was crying after because he realizes he can’t be setting a good example for her and his being jobless, other pressures and mood won’t even allow doing some karaoke even for the benefit of his daughter.
In some of the last strobing sequences adult Sophie appears to be yelling at him to stop (his clubbing behavior).
The end of the movie has him walking down a long corridor and into a room with the recurring strobing lights again. That was the metaphor I went with, that his clubbing was the end of his life. He did offer to help her with any questions on drugs or boys earlier so it appears he wants and plans to be there for her in the future. So my more hopeful theory is he lost his life to his vices from perhaps lung cancer or a heart condition or accident versus suicide a little later in life.