There are really two sides to this argument of if you can be friends with an ex: people either say you can or can't do it. Regardless of what answer people give, it normally comes from their personal experience. They may say to you something like, "Oh, I'm friends with all my exes, it's not weird" or "I tried to be friends with an ex and it was a disaster. Don't do it!" Both sides have some validity here. Is there a way to do it? Yes. Is that going to work for everyone? Definitely not. Let's dive into both sides so that you can decide for yourself if being friends with an ex is do-able and right for you.
The Argument: You CAN be friends with an ex
I've seen it happen, but there are a couple key ingredients that are essential to making this work. Most people who decide to maintain a friendship after their relationship ends have a lot to lose. Maybe they work together or they have mutual friends in common who they spend time with regularly as a group. In these situation, if you can't make a friendship work (or at least be cordial to each other), there's high stakes. This brings us to the first key ingredient which is that it's important to understand why you're wanting to stay friends with an ex. I had a friend who told all of her exes that she wanted to stay friends with them just because she felt bad after she ended the relationship. Guilt is not a good foundation to try to build a friendship off of. Only make an effort to maintain a friendship with the person if you have a good reason to do so. The second key ingredient to making this work is to be flexible with what your friendship is going to look like. Typically, the people who are able to maintain friendships with an ex understand and are okay with their relationship looking vastly different post break-up. Maybe now they only see their ex at group gatherings, work functions, or at the gym they both happen to go to. They are okay with reduced contact which typically means very little or no 1:1 communication or time spent together. The reality is that the romantic relationship ended. If you try to keep doing what you were doing (i.e. texting every day, going to dinner just the two of you, etc.) in a platonic way, it likely won't work very well and may just feel flat out weird. Your friendship is going to look different from the romantic relationship the two of you had and it should.
The Argument: You CAN'T be friends with an ex
There are absolutely valid reasons why you can't be friends with an ex. Some of them are quite obvious such as if there was abuse in the relationship or you both just hate each other's guts at the end of it and never want to see each other again. However, there are plenty of people out there who want to keep an ex in their life because they add value to it. This is challenging to do at times and following the first two recommendations above isn't enough to make it successful. The first big reason that it still may not work is because one person in the relationship still has feelings for the other or there's lingering hurt from how the relationship ended. A friendship cannot happen unless both people are no longer romantically interested in the other. This can take time, especially for the person being broken up with, to fully heal and move on. In many cases, even if they don't want to admit it, one person says "let's be friends" with the secret hope that the end result will be getting back together. The "friendship" is doomed if this is the intention behind it. Another reason why friendships after a break-up commonly fail is because there was no friendship there to begin with. Especially with dating websites and apps, people are meeting "from scratch" more than ever rather than having a romantic relationship bloom out of an already existing friendship. This means that when people say "let's be friends" after their relationship has ended, they have no blueprint for what this looks like because the relationship between them has only been romantic. The people who I've seen do this well had a friendship before they started dating, then they dated, then it ended, but they had something to go back to and a good reason to go back to it. Trying to be friends when you've only been romantically involved with each other is a tough road. It can be best to cut your losses in this case and recognize that if this person was not an important piece of your life before you dated, there is probably not a reason to keep them in it when the relationship is over.
So what's the verdict? The bottom line is that being friends after a relationship ends needs to be something that both people want after they've healed from the break-up. It's much easier to do if you already had a friendship prior to dating each other and it also means accepting that your friendship post break-up is going to look different with less contact. If you follow these guidelines, it can happen. And if you can't? Let the relationship go without guilt.