Very expensive mistake

This stupid careless mistake costs $148. WOW figure right? At least it is for me. So what's the mistake?

I booked air tickets (budget air) for 2, only knowing that i got the same return date as departure after confirmation. I was in a state of shock for a moment. SAME DAY? How come?!

So How?? Tickets are non-refundable. Luckily dates can be changed. Heng rite?

Another shock came into picture. The desired date of return actually cost us an increase in air fare of $41 each. Worst, there is a change fee of $33. So that will be $74 extra each. Well we (my friend and i) could choose to return on the other day, which has a cheaper fare, but we need to pay extra night for the hotel. After cost weighing, we decided to just take the $74 extra, of course, after several 'scoldings' from my friend la. Well, i deserve it. How can i be so careless, not checking the dates before confirmation?? How can i make such mistake?

Well, mistake already made. Think there is nothing else i can do. Feel bad for my friend. Think i will pay part of the extra for him ba. Will see how again.

My last paper ended today, no more exams. Paper didn't really go well, but nothing is much worse than losing $148 within seconds. It's gone just like that. A relatively cheap affordable trip isn't cheap anymore.