The hardest part of partying it up in a long term campaign isn't the planning of dungeons, the slaying of great beasts, or the destruction of evil empires, it's getting to the table and making sure everyone has fun. Both the in and out of game interactions of players and Dungeon Master can be strained at times due to things beyond the control of one or multiple members of the game. Game not being able to be played, the troubles of real life, and people not taking game the same away as others involved can all cause the party and Dungeon Master to get frustrated with one another or the game itself.
As most players and DMs can attest, game is really hard to get played sometimes. Jobs, relationships and other out of game commitments can get in the way of being able to sit with your friends, roll dice and yell about the goblin who stole the party's wealth and hid in the swamps of the Lizardfolk mercenary group. Game should not be your top priority above family, job and such, but it should definitely be at least on your priority list. Because while it is a hobby and a game, it can be very important to someone at the table and that needs to be respected. Your fellow party members are all there for the same reason you are: to enjoy something and hang out with their friends outside the confines of their normal regular lives. Everyone has their own escape from the regular whether it be a TV show, a sport they play or watch, or their weekly trip to the movie theater. If Dungeons and Dragons was a sports team you played in with your community and you didn't show up for weekly practice, then you probably would struggle to stay on that team or at the very least play in the games. Tabletop RPGs are the same way in this respect: if you do not find time for it, you won't play. That's fine if you cannot play as it is not the end of the world, but if you are not honest about this then you will be leaving your friends waiting to fight the dragon for so long that eventually game may never be played again. I've personally even experienced that a few times as a DM where I waited for one player specifically so I could continue my game and while I waited game slowly evaporated around me. I have more than a few unfinished campaigns that I will most likely never get to finish the story of and frankly? It sucks. Both for the players I told had to wait, myself, and the player who just wanted to play and couldn't. I see game like a vehicle, if you let it sit without running it enough then eventually it will die and restoring it will take a lot more effort than people ever expect.
This is why I encourage everyone involved in a game to set what they expect from each other early, if not from the beginning of game. Now imagine this: a DM is writing what they feel is an amazing plot, interesting characters and a story that they feel is both compelling and fun. This DM is working hard on creating a game that they could be proud of from start to finish. The DM is taking this very, very seriously. Now imagine the players do not know this. They think this is just a game for them to mess around with and not take seriously. Something meant for them to only be ridiculous in and not at all care if the game ends next week even. The players think they are just goofing around until eventually they have to stop. This dissonance can hurt or even feel disrespectful to the DM who only wants to have fun while telling an interesting and serious story. The players do not know they are hurting their friend running game and the DM does not understand why they are not taking his game or him seriously. You can even interchange these roles I have laid out to each person involved. Players could want a nice serious game, but the DM is just making it all up on the fly and doesn't really care about the long term story. This is why you must do what people sometimes fear: communicate honestly. Communicate your desires, your goals, and what you want from this game. Whether it be privately or as a group you must communicate with one another to ensure no one is getting hurt because others are unaware of what someone wants. The lack of communication can break a game and I have had it happen to me personally. People did not speak up about how they felt about game and conflicting desires for game can lead to problems that just end game or end it for individual people. The game I played in that comes to mind is a game ran by a dear friend. We were playing a holy trinity of characters, an avenger, a paladin, and a cleric, with a rotating cast of fourth or fifth players on a mission to save the world. Most were taking it seriously and it was running great for awhile, but one individual was consistently late, not leveled up, and did not take the plot they were experiencing seriously enough to even explore it with others or the DM. It got to the point where the DM told him they needed to either drop or start playing game more seriously. The player took it a bit personally sadly and after another game or two they ended up dropping entirely from game. They didn't want a very serious game, they just wanted to joke around and not pay full attention. If I can be honest, it bummed me out. I understood why they dropped and why the DM had to talk to them seriously. There are details I did not list in my story that all led to this point, but for the sake of privacy I will leave it as it is. The DM didn't enjoy losing a player they wrote story for, the players didn't enjoy losing a character they had been playing with, and the player who dropped didn't want to be in a serious story game. If everyone had talked and been honest about their expectations then maybe it could have been different, but no one communicated what they wanted and because of which we were down a player and all a little bummed out. Game recovered and we ended up doing something that many haven't done, we finished the campaign. It was a great adventure filled with amazing stories I still tell my friends when we talk Dungeons and Dragons, but a part of me wonders what it would have been like if that player had stuck around and played to the end with us. I won't ever know and in hindsight I wish before our stats were rolled we all talked about what we wanted out of the game, maybe then we wouldn't have reached that point.
If this post does anything for those that read it I hope it helps you understand that this hobby can mean a lot to those involved. This game can be our escape and our fun in this crazy world we live in. So please, be honest with your friends and party members. Do your best to make it to game ready and able to play. Most of all though, be honest with each other. The last thing anyone wants is another unfinished game or hurt friends.