After seeing a ton of teams and failed companies, I think people fall into two categories. The first group don't care much about what they work on, as long as it grows quickly. The second group is emotionally invested in an idea/space. This is obviously a gross generalization, but you get the idea. There are good and bad manifestations for each group. The anything-that-pops group can over-pivot and never stick it out, but obviously rolls the dice more which improves chances of a good outcome. The my-life-calling group can get too ideological and be stuck on something that's just not working/isn't the right time, but the endurance is necessary for building great companies. There is no right way. I think the most important thing is for you and your co-founders to understand each other's stances and the types of sacrifices you're willing to make. Your stance could also change with experience, so you should check in regularly. Nobody's born with a "calling" and it's developed over time. But should your stances diverge in a significant way, a lot of conflict can result.
For a good breakup, I usually think about 3 perspectives:
1) Relationship with your co-founder(s) - Unless there's some major violation of my values, I'd like to be on good terms even if the team fell apart. That means you might still grab dinner/beer with them and even help them out in their next venture. You all may end up co-founders in the future when you're all wiser and the opportunity presents itself.
2) Reputation with your investors - The VC space is smaller than you think, and you need to maintain goodwill. These investors did make a bet on you, and I think you'd want to demonstrate you tried your best. You might even return some of the money left (it's mostly symbolic, but w/e counts). Most VCs understand failures are inevitable, but you don't want to leave the impression that you were the problem.
3) Self-image/self-esteem - I think many founders underestimate the benefits of a good closure emotionally. A good breakup means you sleep well at night and are content with how you handled things. You don't want bad vibes to fester and ruin your motivation and focus for whatever you do next. Building a company is already hard enough, you don't need the debuff. Doing rash things you'd end up regretting will likely cost you more time and opportunities later.