When my kids were involved with activities  we told them  that we'd make certain they got there  but we would not promise to be there.   The decision was:   What is more important?    That they get to do the activity or that mom and dad are there to watch them.  They were told they were expected to behave whether we were there or not and do their best in whatever they were doing.   They did not need their own personal cheerleaders to participate.   My daughter was a Jr. High Cheerleader I informed her I was NOT driving  an hour one way to watch her jump up and down.   They TOTALLY  understood.  It isn't that we didn't support them  but we needed to have our priorities.   When they were in Jr. High we were farrow to finish 200 sows,   calving 100 cows and just under 1,000 acres.   We worked all day until we couldn't go anymore just taking care of the livestock.....  Save one more pig and that meant $$$ for  ?????.       

Adult children do not need mommy and daddy there to hold hands and cheer them on.    They knew she had it under control  and they were NOT needed to be there.   They WANTED to go to Vegas.