This is a question near and dear to my heart, because once upon a time, I sounded just like the girl you've fallen for: "I'm not ready," "I want to focus on my career," blah blah blah. It was a HUUUGE mistake.
Therefore, this reply has a section for both of you, so I would encourage you to ask her to read it.
First, I will address her: Even if you actually believe in the line you're giving him, I assure you that in saying that you're not ready and that you want to focus on your career, you are either B.S.ing him or yourself.
If you're using these phrases as excuses to not be with him, or as a way to keep him around for convenience without the responsibilities of a relationship, then you need to stop hiding behind these excuses and fess up to your lack of enthusiasm for the relationship, because each day of lies will make the eventual truth hurt even more.
Make The Time, If You Really Want Him
If you're telling him these things because you truly believe that you have no time for a relationship, then you are fooling yourself. I know, because I used to talk the same talk. And where did it get me? I lost the best thing that ever happened to me. I gave up something I loved dearly for something that I frankly don't, out of some perverse and misinformed sense of duty, and I have been miserable about it ever since. If you truly are interested in Ralph, don't repeat my mistake; there is ALWAYS time for a relationship.
Now, to address you, Ralph: First of all, please show her what I just read. Use it as a conversation starter, and come prepared to share your feelings on the situation honestly.
It's Just An Excuse
If she has just been using her words as excuses for not wanting to truly be with you, then drop her right then and there, and find someone who is capable of returning the love you have to give.
If she's just fooling herself, if she really thinks that she doesn't have time for a relationship, reassure her that that's an obstacle you're willing to climb.
I'm not sure what she does, but there are many professions which are very demanding of time, and it's easy to fool yourself into thinking there's no time for anything else.
Help her to see through that by being extra-accommodating to her schedule. Show her your love through the understanding that you won't be able to talk or hang out every night, and focus your efforts instead upon making those nights that you do see each other really special.
Let her know that you're OK with the limitations her interest in her career will bring to a relationship, and maybe she'll come around.
Good luck to both of you.