Juno

The importance of it.

You're supposed to look at Venus and Mars to determine the type of person you want and are attracted to, but you should also include Juno to find out the type of person you need.
Specimen A has Venus and Libra in the First house. This is a person looking for love and validation. She is all about the long term relationship, but she probably isn't very lucky when it comes to finding it. Why? Her Mars is in Sagittarius in the Third house. She's going after really flaky guys who probably give her the run around and not the attention and commitment she deserves. Her Juno is in Virgo in the 11th House. What she needs is some caring, social, practical, and hardworking. She should be with someone she can respect and others do, too. He needs to be intellectually stimulating and very similar in personality to herself (her Sun is in Virgo).
Specimen B has Venus and Juno in the same house (10th) but in different signs (Taurus and Aries, respectively). He both needs and wants someone very businesslike and methodical, ambitious and determined, and kind of dark and moody. He goes for someone of a more romantic and stubborn nature, but he needs someone who is more fun and crazy. This sounds ridiculous because I know the guy, and he should really be with someone very feminine and passive, but his chart clearly says what he needs is excitement, someone who will keep him on his toes. I guess what we need isn't always what we think is good for us. Perhaps he needs a girl who can put him in his place really.
Specimen C has her Sun and Juno in the same sign and house. She needs to be with herself. Her Mars in Scorpio in the First House, so more than likely she will go for what she wants rather than what she needs, and what she wants is someone sexual and selfish.

It's good to be aware of your Juno sign, especially if you keep going after the wrong person. Find out what it is you need, not what you want, and go after that.