Can someone fall back into love with you after fallen out of love?

First you don't really "fall" in or out of love. Love is an emotion you work on, something that is suppose to grow as time goes by. If both sides are not working on it, then it just does not grow and can stop going away.
It is a process that works over time.

So love can be regained though counseling and a lot of hard work from both sides.

But again do not confuse being lonely and missing someone as love,

Do you think falling out of love can be an emotion within yourself that has nothing to do with a partner, like maybe you're not liking yourself?

Can you fall out of love because you don't like yourself or because you don't know who you are yourself yet?

Of course. You fall in love with great expectations and then take a step back and think, "Am I good enough for this other person? Am I likable enough? Will I hold this person's attention, or will he/she get tired of me and turn to someone else?" You can become so obsessed with questions like this that you actually, by your attitude and behavior when you're with the one you love, begin to scare and worry him/her who smells fear and decides to move on.