From OP's affidavit:
16.4 ...
We were deeply in love and I could not be happier. I know she felt the same way. She had given me a present for Valentines Day but asked me only to open it the next day.
http://gretawire.foxnewsinsider.com/2013/02/19/copy-of-oscar-pistorius-affidavit-click-to-read/
I think it's odd that he made an effort to mention how "deeply in love" they were & how he "could not be happier", and that Reeva had given him a gift, but he doesn't mention anything about a gift from him to her. He wants the Court to believe he loved Reeva & would not have intentionally harmed her, let alone murder her, yet he offered no physical evidence of his affection for her in his affidavit.
His affidavit was submitted to the Court as a defense for his actions.
He made it a point to mention Reeva's gift to him, but that is only physical evidence of Reeva's affection toward him, not a demonstration of his affection toward her.
IMO, if OP had purchased/made/planned a Valentine's gift for Reeva, I think he would have included it in his affidavit, to bolster his claim of affection for her & to bolster his claim of his happiness in the relationship, & to bolster his claim that he would not have intentionally killed her. The omission of any such gift from him to her is glaring in its absence.
Perhaps he had planned on going out & purchasing a gift for her the day she met her ex for coffee (remember he called her 2x during the first 20 minutes, which could be indicative of possessiveness, jealousy, checking up on her). If so, perhaps he cancelled any Valentine's gift-buying shopping plan, and instead sulked & stewed about the coffee get-together for a couple of days.
If he's prone to jealousy (which I think he is, based on media reports that I've read about how he reacted to ST dating someone after they broke up), it's not unlikely that he convinced himself that he had a justifiable reason to be jealous & angry about Reeva having coffee with her ex. I wouldn't be surprised if he considered Reeva's ex (or any other male with whom Reeva may have shared time) as a rival. I suspect that he obsessed over an innocent coffee get-together between friends and decided that he had been betrayed.
I think that morning coffee meeting between Reeva & her ex has everything to do with why he shot & killed Reeva on Valentine's Eve, and could be the reason why he apparently had no Valentine's gift for her.