Friend plans trip during birthday party

DEAR HARRIETTE: My best friend booked a trip, and she’s going to be gone on my birthday. I have been planning my 30th birthday for four months; I put so much time and effort into planning it, and she won’t be attending. We’ve been friends for eight years, and I just assumed that she was going to be there. I asked her why she scheduled her vacation during this time knowing that I have my party planned, and she said it was the only time that worked for her schedule. I understand that people have busy lives and that vacations often have to be planned around work, family and finances, but I can’t help but feel hurt. Part of me feels like if attending my birthday was important to her, she would have found another time to travel. Another part of me wonders whether I’m expecting too much and whether I’m making this more personal than it really is.