The Japanese possessive / genitive particle [の]{no} works kinda "backwards" from the English preposition of.
- A of B
A belongs to B → B owns A.
- A [の]{no} B
A owns B → B belongs to A.
It might help to think of the [の]{no} as a little bit like the English possessive -'s ending. A [の]{no} B = A's B.
I think this is partly the reason why Japanese full names and English full names have opposite ordering.
- In English, the personal name is followed by the family name: "Personal" belongs to "Family".
- In Japanese, the family name comes first, then the personal name: "Family" owns "Personal".
(In olden times, the family name was often followed by the particle [の]{no}.)
When translating then, we have to swap the ordering.
- A of B → B [の]{no} A.
- A [の]{no} B → B of A.
Update
Folding in some additional content from the comments.
The OP commented, "it's possible the story is talking about love of summer vacations like it's a movie about a series of summer vacations showing the good things that happen" -- it's certainly possible, but in that case, the title and the story wouldn't have much to do with each other. Considering the meaning of the terms and the grammar, the title 「[恋]{Koi} [の]{no}[サマーバケーション]{Samā Bakēshon}」 cannot accurately describe any story about how someone loves summer vacations.
It could be about the summer vacations of someone named "Koi", but in that case, "love" really isn't the correct translation: names are names, best left as-is. By way of example, the Japanese feminine given name Megumi derives from verb megumu, and literally means "a blessing" -- but when we talk about someone named "Megumi" in English, we don't call her "Blessing", we call her "Megumi". :)