I can relate! 2 weeks ago flew UA LAX-CLE-BOS. 45 min connection time in CLE, have done it a bunch of times before. LA flight leaves 20 late - arrives 7:20. BOS connect @ 7:30. I RUN to the gate - there @ 7:25, door shut, plane there. Rude, dismissive gate agent who wouldn't even make eye contact when telling me to go to customer service to get on next flight five hours later. Rep there was great, was baffled when she saw I'm 1k and nobody held for me (again, used to happen pre-merge days for those close calls). Super frustrating all around.