In what circumstances were Nightcrawler and Scarlet Witch falling in love with each other? And why (if it's not obvious) ?

According to what I know from the Witch, she's very easily offended (because of her tough youth) and when she is angry, she leaves massacres behind her.
Nightcrawler is, for his part, almost the opposite of this woman. He is of a quiet nature, sometimes comic. He forgive easily the ones who offend him and he'd fight just if he has no choice.

So how did they end up loving?

Thanks in advance for your clarification...