Honey, Valentine's Day is about YOU, the girl, you do not buy guys stuff on this day. Maybe a little booty and they will be happy...This is YOUR day to get the gifts, the flowers chocolates kisses and such is all for YOU. He wants space, give him his space, possibly just let him go, b/c if he loved you he would be with you on this day or try getting you back, not have you sitting by yourself...If I was in your situation I'd just leave him alone, go out there and find someone else. Your way to good for him! get yourself a man! Hope everything works out though, best wishes.
Based on past experience, my guess is that "I need space" is the most gentle way he could think of to say "I want to break up." The ball is in his court. He's the one to make the next move since he's the one who initiated the change in the relationship. Go about living your life and be open to other possibilities. But be aware that--and again this is from my personal experience as a male--pushing too hard for a long-term committed relationship and/or time-consuming expectations is exactly what prompts a man to "want more space". Contacting him now in any form is probably the worst thing you can do. You are more likely to get him back by letting him know, by abstaining from contacting him, that you respect his needs.
He is either trying to break up slowly (so as not to hurt your feelings) OR he is trying to worm out of buying a Valentine's gift. If he tries to get back together in the next two days....tell him you liked the whole space thing and want more.