WIBTA If I (28F) didn't attend my brother's (28M) international wedding?

Longtime lurker, first time poster.

My brother and I are friendly but not particularly close - no real reason, just didn't hang out a lot after we moved out from my mom's place.

My brother has taught English in China and Vietnam over the past several years and is currently living in Vietnam. Things seem to be going well for him but we haven't really been in touch. However, he did fly back home to come to my wedding last year. We announced our date well in advance so guests had about a year and a half notice (we had plenty of family out of province/country so we wanted to give people time to make plans). Despite us not being super close, it was nice to have him there.

Last week, I got the news (via my mom) that my brother got engaged to his on again off again girlfriend (who lives in Vietnam). Very exciting! However today I found out the wedding date is May of this year - approximately two months from now! Plane tickets to Vietnam are about $2000, not to mention having to scramble to take off work for both myself and my partner.

My brother said he understands if I can't make it given the short notice, but my mom really wants me to go and has guilted me about it because he came to my wedding. I don't think it's quite the same given the huge difference in notice, and also this would be a really big expense for us.

For some extra context, my brother has been able to save tons of money while working abroad and travels frequently, while I live in one of the most expensive cities in the world (cost of living is stupid high) and have never gone on an airplane vacation as an adult...

My partner and I were just starting to think about a belated honeymoon and this would blow a hole straight through our savings for that.

Part of me feels very guilty and like I'm making excuses not to go, but I do think it's a huge ask with very little notice. So, WIBTA?