I usually just drop it, unless we were really good friends before.
I let it die down naturally and gracefully by just calling/text/hanging out less. I will still do these things, but by gradually letting it die down, there's less anger/resentment/awkwardness [especially if she's friends with (a) friend(s) of yours; if you're boyfriend-girlfriend for a long time, this will naturally occur].
Negatives that usually happen:
- She says that she wants a friendship, but then will never hang out with you or responds to a call/text weeks later (which is just a nicer way of "never hanging out with you").
- She dumps all of her emotions/problems on you without asking about yourself. Also, usually when guys (or at least me) are sad/upset, we just want to be alone anyway and don't want to talk about it for hours, so again, she just ends up talking for hours. You're not her boyfriend, and she's not even really being a friend here. She's wanting to unload/vent so that she can spend good quality time with her real friends without bringing them down.
- You broke up for a good reason. You weren't compatible or got in arguments or on different paths or at different maturity levels or a huge number of other reasons. Staying close may make you end up going on dates again and forming the "on-again-off-again" relationship. Luckily, I've only done this once in my life and on the first girlfriend I ever had. It's stupid and immature. Move on.
- She meets your new friends or lovers and badmouths you. With lovers, this is usually jealousy but can be resentment (this usually hurts you and is a huge negative, but can also make your lover jealous and admire you as desirable). With friends, this is usually resentment or saving face. The resentment can come from you breaking up with her. As a side story, I had a girl breakup with me and badmouth me to my friends. I think this was due to how she broke up with me: she just stopped talking with me, and I found out through a friend. So, in this situation, I think she was trying to save face in case I badmouthed her. My true friends of course knew this was bullshit, and I never had to badmouth her back.
Ones that I'm not as familiar with but have seen through my friends:
- She uses you as a backup. (And you may also be using her as a backup. I don't agree with this, but I won't judge you poorly for doing it -- who am I to judge?)
- She wants to keep tabs on you. This falls in line with #4 above, but is a little different.
- She just wants to date your hot friend or use you for some other reason.
This is quite a long list of negatives, but again, this doesn't always happen, but I see it a lot.
The positives I've seen:
- Friendship, if this is truly mutual. This is good if you don't have a lot of friends that are girls so that you can get a girl's perspective on things: fashion, relationships, buying your mom a present, etc. Personally, I think it's best to just get friends that are girls without dating them first if this is what you're looking for -- and this is actually pretty easy. However, you formed a relationship in the first place because you had things in common, etc., and you probably shared a lot of personal details with each other, so sometimes you can maintain a really good friendship as well.
- If both of you can keep your emotions in check, you can maintain a sexual relationship. This has negatives though. I've seen guys less willing to go out looking for girls because of this.
- Hook you up with a hot friend, etc. This has negatives; I'd suggest reading Chase's article on the negatives of dating within your social circle.
I'm sure that I'm forgetting a lot of positives and negatives, but that's all I can think of for now.