A Grande Moral Dilemma. Help?!

So! A month ago now, I put in a request for ONE weekend off. Unpaid. I will be out of state for something VERY important to my partner, although not technically a thing we NEED to be at for our current livelihood.

For a little extra justification— I work openers. I stay late 75% of the time I'm asked to. I pick up extra shifts/take other folk's shifts OVER 75% of the time I'm asked to. I happily do the gross cleaning tasks people don't like, trash runs in bad weather, and hop in to deal with rude customers, the whole nine yards. I do my best to make sure that every. Single. Day. That store and my coworkers are set up for success. I consider myself a VERY good corporate bootlicker, to be perfectly frank with you...

My manager gave me ONE of the days off that I needed, and essentially told me I'm SOL for the rest, because she FORGOT to approve me when she saw it A MONTH AGO, as well as when I reminded her semiweekly.

I've put the remaining two shifts up for grabs on partner hours— but I sort of have a feeling they won't be picked up. I'm a week out from the trip out of state though, so we'll see where the cards fall.

I know for a fact that if I cannot get these shifts snagged, I WILL just have to call out. I literally will not be IN THE STATE that my location is in. But I'm having a really hard time grappling with how much it could inconvenience the folk I open with... Other baristas, would you be upset/irked with a coworker for calling in over something like this? Do you think it'll cause any conflict between me, my coworkers, or my manager?

Edit: Lots of appreciation for the folks commenting !! I tend to overburden myself in the name of 'not being a burden to someone else' but !! Maybe I should give myself a little more credit haha