I am really sorry for the small amount of details, and I'm not even sure it is an English movie.
As far as I remember, a young guy who works in an old diner/restaurant (may be a pizza place) one day goes behind this restaurant/diner/or whatever place to bring something, and he accidentally discovers a magic door which takes him to another universe or a heavenly kind of place. In there is beach that I can remember, and the first time he goes into this place, the air is not even like air. For example he touches the air with his fingers and it is like water, or like the scene in The Matrix when Neo touches the mirror in the first movie, and the mirror acts like plasma, but only it happens in the air in the movie.
Then this young man meets a girl and they fall in love. Even though I am not sure, I think some bad stuff happens in this world too, and this young man turns back and consults his boss or maybe father, and decides to go back through the door to that world again to save the girl.
I have seen this movie when I was a little kid. Not even sure it is an English movie, because I watched the movie in another language and the name (again, not sure, just guessing and remembering that way) was "Chinese Restaurant's Door" or something like that.
I am really sorry for the small amount of details, but this is all I remember. like I said, I watched this a long time ago when I was a kid. It was probably a '90s, or at the very latest, early-2000s movie.
Edit: I can't remember the time, but it was a dubbed movie on TV, and I don't know what the original language was (could've been be English). I watched it between 1997 and 2000, but since it was on TV, it might have been produced years earlier. The ethnicity of the characters was white European, and it is a definitely a family movie. I don't remember anything more than this.