I'll try to not go too deep into detail and this might turn into a small rant, so sorry in advance. For easier reading I added some subtitles. ;-)
Here is some context
My group and I (4 players, amazing DM) play for almost 2 years now and it is the first rpg group for all of us. It was very clear early on, that we have different playstyles (mainly me), which is mostly fine. While the others are more focussed on combat and doing their own thing in character, I'm more of a role-/teamplayer. While I also like some good old chop chop action, I love playercharacter and NPC interactions just as much. Now we do have one main plot hook, that keeps the characters together and until a few months ago this was enough to keep the group in a relatively good state. My character seems to be the only one with enough social capabilities to be able to get some higher standing NPC contacts and drive the group into a direction where we can actually rally some folk and do "big stuff" (meaning: fight devils - level).
The problem
Now the other PCs did some things, that don't sit right with my character and actually threaten my PC's life. So I tried resolving the problem by talking with the group in game (my PC mentioned his concerns two times before) where I was met with no understanding and my concerns were quickly dismissed and even made fun of. This really bothered me out of game, so I talked to the players and asked them to be a bit more forthcoming in order to make it easier for me to justify that my character stays in the group despite those differences. This was met with some ambivalence and I don't feel like they really cared - it felt kinda like they were saying "Well it's your problem, not ours.". Now I admit at that point (our latest session) I took their ignorance personal and their reaction (or lack there of) hurt me. From my point of view I had done so much for the group in and out of game and now they are not willing to have one (in my eyes) small nice moment of appreciation with my PC, which also doesn't cost them a thing, to make me happy? It also bothers me that somehow the other characters are way more friendly towards some random NPC than they are towards my character who has gone out of his way to help them or do them some small favors (which they have never done for my PC so far).
My role in the group
As I mentioned before, we have very different playstyles and I don't mind accomodating to them so they can have their fun moments. This situation though has bothered me for a while now and I find myself enjoying the game less, cause I seem to ALWAYS be the voice of reason in the group (e.g. making them take prisoners instead of butchering everyone, not stealing from the king etc.) without anyone actually listening or appreciating those efforts. Being the reasonable one was the job I was aiming for by creating this character, but they make my job so much harder than it needs to be and take the fun for me out of it... We all want to play this amazing story our DM has created for our PCs specifically and are invested, but my fellow players are not at all invested in any other PCs than their own. Which is fine I guess, but I feel like my wishes for more in game teambuilding (or at the very least not giving reasons to leave the group) are not being heard.
Talking to the DM
I talked to the DM about this (maybe I am the problem?) and he understands my side and sees the problem, but doesn't know how he can help. He also mentioned that if my character were to leave the group, the other PCs would have a hard time driving the plot forward cause, as I said, my character is (I guess thanks to my roleplaying-affinity and the DM rewarding that) the only one with considerable ties to important NPCs.
Also
I'm all for doing silly stuff and we have a lot of fun memories, but because of plot, we now have to act and think bigger than "tavern shenanigans" and becoming small "village heroes". Killing some monsters in the woods for some gold doesn't cut it anymore. I really love the story and want to see where it takes us and how we can shape the world. And despite my rant, I like the other characters as well. I think my group has tremendous potential, but if they continue to refuse to acknowledge the obvious in game problems I don't see how this group can work for me anymore. It's a game after all and isn't it the responsibility of all players (and DMs) to make sure that everyone has fun?
Some advice please
Have you been in a situation like this? What did you do? Should I just drop the in-group issues? Should I move on and focus just on my fun and my characters journey and "ignore" the actions of the other PCs?