Examples: Miaka and Tamahome... Bulma and Vegeta, Chi chi and Goku, Ranma and Akane?? Miki and Yuu, Meiko and Na-chan...
Reasons for breakup?: Pure jealousy. Valid enough...
The How-to: For the males, if you wanna get the girl, here are the only options: Kill the rival! Yes kill the poor suckah. Be friend the hottie, kill him cruelly, steal the girl!
Get plastic surgery. Learn to talk and act like your rival. When I say plastic surgery, remember to fix everything... I MEAN EVERYTHING, down to your toes. Women can tell their lovers' toes apart!
Persist! Be nagging and annoying til the only option for the girl is death. She'd accept you... perhaps. Bulma would bash you endlessly...
ROMANCE HER AWAY! Poems, roses, anything romantic will sure melt her heart. She might put you behind your rival, but hey, the sucka will sure die one day. THEN IT WILL BE YOUR TIME TO SHINE!!
For the gals, well if anime guys weren't so perfect, it would be much easier. Sigh eh? You can try out the techniques listed above for the guys. Or you can play the sad, lonely, I HAVE NO ONE IN THE WORLD role. Melt the guy's heart with your pathetic life and he's yours. HE CAN'T RESIST PLAYING THE HERO! mwhahaha
Examples: YUU AND MIKI AGAIN!! Usagi and Mamoru... Fuu and Ferio. Relena and Heero??
Techniques for the guys: Well... I dunno actually. These couples are pretty hard to break apart. Besides, I rather like the coupling of Miki and Yuu. That's why they are every where, baka!!! To get Miki, it's easy, but YUU??? Hey this guy is a tuffy. Miki is the only girl for him. Beauty doesn't get to him. Mebbe the sad approach. Look, I'm dying, I need you. He may fall for that. or a Miki-look-alike who is ten times better. CAN COOK, CAN CLEAN!!!
For Miki, just be cute. gasp!!!
For Usagi, offer food! Lots of food. A man who can cook and is hot, is the man for her.
For Mamoru... well again... look at all the senshi around him. if he doesn't fall for any of them, I don't see how or why he would fall for you!