It's hard to say goodbye to something you love — and there are a lot of people right now who absolutely love Bernie Sanders' presidential campaign. As well they should. It has been one of the most remarkable happenings in the recent history of American politics, as a rumpled, crotchety 74-year-old socialist put together a serious challenge to the Democratic Party's anointed candidate, raising over $200 million and energizing young people across the country for a revolutionary crusade to remake American politics.

So you can understand why Sanders supporters have trouble accepting that there's just no way for him to be the party's nominee. Part of it comes from the fact that, technically, it's still possible for Sanders to prevail. Yes, it would require him to persuade nearly every remaining Democratic voter to cast a ballot for him, and then get all the superdelegates now supporting Clinton to flip as well. So who knows?

Here's the brutal truth, though: No matter how the big prize of California comes out next Tuesday, Clinton is still going to have a majority of the delegates and is still going to be the Democratic nominee. As Harry Enten has observed, it's a near-certainty that Clinton will officially pass the number of delegates she needs when New Jersey closes its polls at 8 p.m. eastern on Tuesday. Even though the California primary looks to be extremely close — the widely revered Field Poll shows Clinton leading Sanders by a margin of 45 percent to 43 percent, and other recent polls have found similar splits — since Democrats allocate delegates proportionally, the two candidates will gain similar numbers of delegates. It won't matter at that point who nosed out who in that last big contest.

But tell that to a Sanders supporter, and you'll likely get an earful of protestation. That's not because they aren't rational people, it's because they have so much invested in his campaign — often financially or in terms of the time they've spent, but mostly emotionally. Bernie has promised them so much, and the campaign has accomplished so much, that saying, "Oh well, we gave it a good shot but it didn't work out" must seem like a betrayal of everything they've been fighting for.

Hillary Clinton has offered her supporters little in the way of grand dreams and glorious visions of transformation. She's a pragmatic politician presenting a pragmatic program. Sanders, on the other hand, is a candidate of revolution. He asked his supporters to believe in something epic, to change their thinking about what's possible in politics. If you Felt the Bern, you yourself were transformed. To admit that the campaign is over means admitting that the dream is dead, and that person you wanted to be — hopeful, committed, optimistic — was wrong about what was possible.

Add to that the fact that Sanders supporters have convinced each other that the system is rigged, which means that any outcome other than Sanders winning is not just unfortunate but fundamentally illegitimate. If you believe that, it means that once you assent to a Clinton victory you've assented to corruption.

While Sanders himself has gotten some criticism for not bowing out already or acknowledging that it's all over, you can't blame him — and when you watch him being interviewed in recent weeks, you can see his internal struggle. He surely feels that at the very least, he has an obligation to stay in the race long enough for all his supporters to have the chance to cast their ballots for him. And it would be weird to say, "I'm still in the race, even though I know I've lost." So he can be forgiven for putting the best face on things, even if it sometimes means he has to stray into fantasyland. "If we win California, and if we win South Dakota, and North Dakota and Montana and New Mexico and New Jersey, and the following week do well in Washington, D.C.," he told rapturous supporters this week, "I think we will be marching into the Democratic convention with an enormous amount of momentum."

Which is, of course, ridiculous. First of all, he's not going to win all those places. But even if he did, Clinton will still have passed beyond the majority of delegates she needs. After all the voting is done, "momentum" is irrelevant. It's like saying that even though your team lost the game 5-4, the fact that you scored a run in the ninth inning means you ought to be considered the winner.

Even after all the TV anchors and newspaper headlines declare that Clinton is now the nominee of the party, there will be a few Sanders supporters who refuse to accept it (and those few will surely have no problem finding cameras into which they can air their grievances). They'll say Bernie can still make his case to the superdelegates, that they're holding out for the FBI to indict Clinton, that it was never a fair fight to begin with. If you feel the urge to mock, consider sparing a sympathetic thought for them.

They've come a long way, and their idealism is something our system needs. And eventually, even if it takes a while, they'll make their peace with defeat.