Don't really need practical help on this, as much as I thought would be interesting to hear thoughts on it.
The strange thing about romances is that , on the one hand, we have to root for the couple, and believe that they belong together. On the other hand, there also has to be personal issues keeping them apart.
If the characters are too perfect for one another, then the only way to keep them apart is some big misunderstanding or contrived reasons. The characters hold off on becoming a couple just because they're not allowed to be one until the climax. If the characters have too much conflict between them, then a relationship seems totally implausible or actually undesirable. For instance, the 'bad boy' is so bad he should probably be in jail, instead of being reformed through the Power of Love. Also, Constant bicker = They must be in love!
For those who write romances or romance subplots, how do you try to balance this?