I am going to respectfully disagree with Lagirl on this one - to a certain degree.
For a man, he is more driven by his purpose in life than he is by relationships. A man measures his own personal success and self worth/respect/esteem with his purpose/work. A woman measures her own personal success and self worth based on the quality of her relationships. When a man does not have his life together, he has a very difficult time being in a relationship. I think John Gray, Men are From Mars, talks about this, but I may be wrong on that.
I do think you are correct that the timing of your "talk" was certainly off. I also think that there has been maybe a misunderstanding of what he heard and maybe what you want.
If what you are asking for is exclusivity, to me that would mean that you want to establish that you and he are only dating each other while you figure out if what you have is going to develop into a relationship. What your guy heard (mostlikely) is that you want a relationship which in his mind equals marriage. While he may not be able to verbalize this or understand it, men don't understand what a relationship means to a woman. Also men understand the social norm is that women dream about marriage from a child, where men don't think along those lines at all. They don't want a relationship to have a relationship. They fall in love with a woman and want a relationship with her.
You may have been very specific (which you need to be in communicting with men) when you told him you want exclusivity/relationship. Or you used those words, assuming you both had the same definition for those words.
I believe your guy cares about you, but his life is not together enough for him to consider himself to get into a relationship with you. I think this is why he keeps texting you and texted you on V-day. He cares.
The question then is where do you two stand and how to proceed?
Are the two of you already exclusive in that you two are only having sex with and dating each other? If you are already there in actions, then what is it that you were asking for? If not, then just taking the step of being exclusive and him saying no, I would move on. Being exclusive is not that big of a step for a man.
If you are asking for a relationship, what does that mean to you? What is the structure of that commitment. For example, you two are only seeing each other, you see each other 3 times a week and talk daily, or whatever it is that you want.
Since he is still contacting you, I personally would talk to him. Figure out the structure of your relationship whether it be platonic friendship and if that means no contact for a while or if you two can re-discuss what it is that you specfically want and if that works for him too.
I don't think this guy yet has done anything to be completely cut off. I think you two of a little unfinished business that you need to sort out.