I've made many more mistakes than this, hence the draft, but...
  1. Getting back together with an ex
    Sometimes it works out. My boyfriend's brother and sister-in-law broke up and got back together and it was right. But a lot of the time the reason you broke up hasn't changed or gone away, and isn't likely to any time soon. We broke up abruptly and "too soon" and "didn't give it a real shot" and we shouldn't have.
  2. Continuing to sleep with an ex
    Yes, the sex is good. No, you are not removed enough from the breakup for this to be a remotely good idea. Especially not for 7 months.
  3. Refusing to let someone ghost
    Forcing someone into saying "I don't like you enough" doesn't make anyone feel good, but obsessively trying to pull an answer out of someone is a bad call on your (my) end.
  4. Not listening when your friends all hate your significant other.
    If literally everyone in your life hates him/her, there's probably a reason for that. And they're probably right.