Very much personal posting but other aros might relate
I love being aro, it's extremely cool, it's a big part of who I am and love it
BUT, that fact does nothing to alleviate the resentment I end up feeling for the best friends who say they'll always be there for you and "oh, we'll all grow old together, we'll be telling shitty jokes to each other at a nursing home at some point", only to immediately show you that they will in fact always prioritize a romantic pursuit by bending over backwards to have everything be about a new love interest they met less than a week ago
In my case, some of my best friends live in a different city hours away from mine, so we can rarely hang out in person anymore, and they also have huge anxiety problems, so they haven't visited my city at all, it's always me going and telling them "I'm all yours when there, we have to go out!" And so many times we don't even get that as plans fail so easily. And plans have been made for them to visit the other way around, where us the remaining 3 people of the friend group are. But it's always a faraway hypothetical that never goes anywhere. "Some summer", "over spring break", "It'll happen I swear".
These two friends in the other city each got romantically interested in some guy
Friend A, who fails to meet our plans to go out 95% of the time, somehow managed to always have the perfect hole in their schedule to go out at least twice a week for a month and a half with their romantic prospect
Friend B, who's been saying they have to visit our city at some point but hasn't because of anxiety or being busy or financial problems, met a guy less than a week ago who lives in yet another city that's just as far away as mine is from my friend's city, but in less than a week they've already made plans to go on a trip to their crush's city to see them more and go out
Because you are understanding with them
Of course it's hard to go out, we've all got different responsibilities and different mental health issues and different money issues and such
But after being best friends for almost a decade and seeing them suddenly be completely able to do in a day what they fervently insisted they couldn't do with you in a year, it's.... Maddening
I'm not jealous of their partners because they have their romantic attention. I'm envious of the time they can clearly manage to give someone they've barely met but is obviously immediately more important until the relationship implodes than I am having been there for them for nearly a decade
And it means that when the relationship fails and we're back to the status quo, I have to sit there and believe them that it is still literally impossible to go out for more than 2 hours every 4 months. I have to sit with the fact that as soon as some other pretty person catches their eye, "we're all gonna grow old together" becomes nothing but a passing joke