Cruising around Jerry's drive-in restaurants on Friday nights in the early '70s was the fun thing to do after being cooped up all winter. If a guy was lucky he might meet someone he liked and end up with a phone number. However, he always took the risk of rejection. But usually, like anything else, you don't find out unless you ask.
The same is true for a songwriter who pitches a song to a publisher, singer, etc. They may like the song, but the odds are in favor of rejection.
Handling rejection may determine whether the person gets a second chance with that publisher. Getting upset reduces those chances. The songwriter with the best chance of making it must learn to be graceful. There are many publi and they are all different to some degree. If they offer advice, listen! You may learn something that will improve your song or your writing skills.
Consider yourself lucky when a publisher takes the time to listen. Don't ask them to play more of a song if they have cut it off. Why should they spend two or three more minutes listening to something that they are almost certain they can't use. They were considerate enough to listen. In turn, be considerate of their judgment that out of the several hundred songs they've heard this week, they don't want to listen to two more minutes of a song they can't pitch or know they can't convince a producer to spend $1,000-plus to produce and promote.
One of the drawbacks of the songwriting profession is being rejected. Every successful writer has experienced it, so don't take it too personally. Smile, thank him or her, save your fussing and cussing for the privacy of your car and have a better song next time around.