I messed up so severely that I think my relationship is officially hanging by a thread. I knew my girlfriend's birthday was in late August, but in the chaos of quarterly deliverables, I lost track of the calendar and completely mixed up the exact date. On my birthday four months ago, she stayed awake till midnight, sent a personalized collage, and coordinated with my friends to surprise me. Today was her birthday. I didn't wish her until she sent a single text at 3 PM saying, "Thanks for remembering." My stomach instantly sank into an abyss. I've called her seven times, sent apology voice notes, ordered an emergency floral bouquet to her workplace, but she isn't picking up or reading messages. I don't blame her. Forgetting your significant other's milestone day when they treat yours like a national festival is unforgivable. Any advice on how to salvage this before her birthday turns into our breakup day?