| When your lover tells you're a good friend, it's bad. It shouldn't be that way really, after all the things that make for a good friendship all ought to be found in your partner. If you are lovers and not friends, that ought to suggest a problem.
Unfortunately, most of the time the friendship part of love is taken for granted, assumed within the context of the deeper relationship. By both of you. So when your partner says that you're a true friend, that almost always means they don't want to love you anymore.
I've heard it many ways. Sometimes it's sugarcoating for a bad pill. Or an attempt to escape guilt. Once it was a compliment, for a lover who never wanted me for more than sex, and discovered I brought her more than a few tasty orgasms. She had been hurt badly, and when I met her preferred casual sex to the deeper satisfaction of romance. I've seen that before in people who have been abused. These people fear forming real attachments because they don't believe themselves lovable. No one can hurt you like the one you love.
But most of the time it really means that they want to break up. Breaking up is a part of life. For most of us, one great relationship is all we get, or need, per lifetime. All the others are footpads on the way. Necessary steps to teach us important lessons about ourselves, our needs, and others. Much of the time, break ups occur at a point when we realize, that this person can't or won't make our dreams come true. And you want to tell the other person that while this isn't going to work, that they still matter.
No matter how good the reasons, when someone leaves you the break up leads to self-doubt. If the string of failures seems endless, perhaps it represents a capstone upon a pyramid of pain. A long enough string of failures can make you wonder if the whole romance thing is worth doing. I've been there before too.
At one time I sort of hoped I'd be neutered. Not surgically, mind you, just get to a state where romantic and sexual feelings didn't occur to me. I could be 'just friends'. Then I wouldn't ever have to lose anyone. Then no one could ever really hurt me again. After a bad breakup a couple years ago I calculated my Romantic Happiness Index. I simply took the number of happy months I'd had in romances and divided it by the number of months I'd spent agonizing over my failures. The numbers weren't good. It came out that I'd spent three months in agony for every month of joy.
Based on those numbers, I made a rational decision to never date again. It seemed perfectly sensible, given that the legitimate possibility of finding true love was overshadowed by the near certainty of another romantic disaster. Multiple disasters, probably. But people aren't built for celibacy or solitude. Sex is a primary biological drive. If it weren't, we'd never have made it as a species. Sooner or later, women started looking good to me again, and I dated again, albeit with shields set on maximum.
But even if you both really want to be 'just friends' it's hard. You have to watch your former lover with a new partner. On the radio program This American Life, Ira Glass once described shopping with his ex-girlfriend as she picked out daring clothing to wear for her new lover, on the radio. It was excruciating and it made him question their entire relationship. 'Friendship' was good for her, but not for him and the pain of watching her go away--- particularly when he himself was alone-- made him flee.
Asking your ex to help you dress for another man isn't the height of sensitivity. Most of the time, people have more sense than that. Of course painful subjects will come up, but painful subjects come up in purely platonic relationships. Friends forgive each other. Forgiveness is a necessary part of any long-term relationship.
But both of you will eventually date again. Maybe you already are, as the breakup came to clear the road for someone else. That other person will always know you two were once more than friends. They will never feel truly secure around you. Especially if your ex spends significant time with you. If they moved in on your lover while the two of you were together, they may expect you to bear a grudge. Surely you owe their relationship no loyalty, because it came at your expense. You might start something again. After all, it's what they would do in your place. Sometimes spending time with your ex puts your new relationship at risk.
And so a lot of the time, It's really hard to be just friends. That doesn't mean that it can't be done, but there are plenty of obstacles in the way. Usually, 'just friends' means you chat at parties while your lives drift apart. | 
