So, what needs to be taken into account when naming your book? Searching. You want a reader that is specifically looking for your book to be able to find it. If I search for "The Forever Girl", will that be the first thing that Amazon or Google pops up? Well, I'd hope so, otherwise, you're losing readers that are truly interested.
Now, for some examples. My friend, Glenda Poulter has a book titled Welcome Home. From what I've heard, it is a good book, although I have yet to read it. If you search "Welcome Home" in amazon, it returns 47,372 paperbacks. I will never find her book that way. It doesn't even show up in the first 100 search results. Fortunately, I can find it very easily by searching her name. But not everyone will remember your name. They may remember one or the other, but maybe not both.
Another example is Riley J. Ford's Into You, which is on my list of books to read. "Into You" returns nearly a half a million paperback results, although Ford's book, thankfully turns up first in the search results. I can't guarantee that this isn't because I've been to that page before, though, as search engines tend to be dynamic. I couldn't find this book at all on Goodreads.com and had to add the entry for when I eventually reviewed it. Because the phrase "Into You" is part of a lot more titles that just exactly what I searched, it returned a lot of variations of the title that I didn't want.
I am currently reviewing Heart Song by Samantha LaFantasie. "Heart Song" returns 24,440 paperbacks. LaFantasie's book returns 6th in the search results.
So, I'll close with a word of caution. Do some research before settling on a book title. See how many titles come back when you search a title you are interested in. Tens of thousands might not be bad (even The Forever Girl returned nearly nine thousand results), but I would seriously reconsider anything that returned in the hundreds of thousands range. Be a big fish in a smallish pond, not a zebra fish in an ocean.