
There are many types (and colors) of guava. The only reference to Asian guava I found said they were white inside, so you may be leaving yours on the tree too long. Or it may be a type that's just not as sweet as you had hoped. Here's an article on guava growing: https://www.gardeningknowhow.com/edible/fruits/guava/growing-guava-fruit-trees.htm
That being said, of course you can make jelly from guava. And candy, and many other things. Here's a link to just one of the dozens of guava recipe site you can find online: http://www.tfgsf.com/?page_id=552