Each book can stand alone and can be read in any order. If you do choose to read the books in order, you will see some characters pop up again from previous books--fun Easter eggs, but not necessary to enjoy and understand the current book.
Admittedly, I'm a disaster on a soccer pitch, but I've been a "soccer mom" for years. I decided I'd better put some of that experience into a book. Turns out, it's a lot more fun to write about soccer than to play it!
It really is okay to read these books in either order. Yes, you'll see the main characters from Love for Keeps in Santa Cam, but barely. And I don't think it's too much of a spoiler to know they eventually get together. But by all means, read them in order if you get the chance.