Cancer and Libra immediately are a sparkling and romantic affair. Cancer needs romance, and Libra needs it even more. So each of them is willing and open to exploring not only the sensual side of the relationship, but what I call the magical side. Let's make magic in this life. Let's go places and do things that create something sparkling.
Libra needs a lot of attention. Libra likes to be coddled and looked after. Libra can be lazy in certain ways, and I'm also talking about emotionally lazy. Let someone else look after me, let someone else do the protecting and go and make money, and treat me the way I should be treated. On the other hand, Libra also is goal oriented. Libra can be ambitious. Libra wants to be in a partnership, and so Libra will bring energy to that partnership.
Where they start to break apart is that Cancer is deeply feeling, deeply sensitive, and Libra is more thinking in its relationships. Libra may think it is romantic and deeply feeling, but actually Libra thinks about feelings and Cancer feels feelings. So you keep running into this emotional quality that seems to be missing in a Libra. It's there but it's not as potent and not as concentrated as it is with the Cancer.
So the emotional quality kind of dissipates, and pretty soon the Libra gets tired of Cancer clinging or Cancer's needy ways or Cancer trying to control the other. Long-term, it takes a lot of work and energy and really commitment to make this pairing last.