2 years is a good distance
Don't believe them when they say they got over you. Don't believe yourself if you hear yourself saying out loud that you're over them. Painful breakups don't vanish just like that. The more painful the breakup, the longer will those memories block your view from enjoying everyday, sober reality - and even more so a meaningful conversation with the person.
I found one thing that worked reliably. It's taking two years to heal.
Six months is too short. You still want to go back and apologize or ask questions or blame the person or pretend the sour ending never happened. You'll ask the wrong questions, you'll say the wrong things, and it will just exacerbate the things that irritate either of you.
One year is still short. It is the first time that you're spending this time of year alone or with someone else. There will be sexual tension. The person will look more beautiful, or more desperate, or more like your father, or whatever it was that attracted you to them for the wrong reason in the first place. At best you'll have a good, polite conversation and pop in and out of each others life while feeling increasing amount of déjà vu while talking, or while not talking. A weird aftertaste of being stuck between two rocks.
Two years is usually good enough. You still know what happened, but unless you've been obsessing daily about the other person, you're distant enough to talk about it if it needs to be talked about; or not talk about it if you've grown enough to understand, or let go, successfully. You know the person well enough to be a friend again, and you respect yourself well enough not to date them again.
Three years is long. You're different people by now. What happened, happened, you're too smart to dwell on the past, and you still enjoy the sense of familiarity that never goes away. You might as well start flirting and repeat the same mistakes again.
