This might sound like philosophical one-liners, but IMO:
If anyone's ever loved and lost, the ever elusive romance might be easier to relate to. It takes heart not to let anything stand in your way, even if it leads to disappointment. (HA! cheeseball marathon, coming u..p...)
I believe a true hero / villain are at their most powerful when they show affection, and a human-like quality even if their motives aren't always on track. People might hate what a villian does, but can sometimes completely understand once they understand why they react the way they do.
Fighting for something seemingly unattainable happens in many facets other than a love interest, (money, and fame which are also not foreign to comics)
Would I like to see what would happen if Catwoman and Batman gave it a good honest go? Of course. Based on what I know, I can't say I could see it working, but then again their history would lend itself well to a story maybe driven by the loss of one another. The yin to the yang shall we say.
.....You might call me soft, and for that I don't blame you.. just understand that once Batman decides to hang up his boots, he may be inadvertently hanging up Catwomans also....and who wants a one dimensional dynamic? Mr. and Mrs.Smith made it work! haha.. now they have kids from 405930 countries.