I just posted on another thread that I think that astrologers who equate signs with houses cause a lot of confusion.
A sign shows how or in what manner a planet works.
A house shows where, or in what area of life a planet works.
Note also, that each planet, sign, and house rules multiple phenomena. Venus rules love, but she also rules the fine arts, luxuries, professions associated with women, and many more, besides. Mars might be the man (real or hoped-for) in a heterosexual woman's chart, but Mars is also her innate assertiveness, aggression, athletes, soldiers, and surgeons.
Venus in Libra is very strong in the sign that it rules; but in the 12th house, you may be hesitant about open expressions of affection. This would be a good placement for an artist, who needs to work alone.
With Aries on the cusp of your 7th house of marriage and other committed relationships, you probably want someone who exhibits traits that you associate with Aries, whether this person has any planets in Aries or not. These traits might be independence and courage. Given that the planetary ruler of Aries, Mars, is in Taurus in the 8th house, some sensuality wouldn't hurt, either.
It's fairly common for different pieces of the horoscope to contradict one another. Astrology aside, maybe you see contradictions in the people you know.
Good books for beginners are:
Steven Forrest, The Inner Sky.
Robert Hand, Planets in Youth. (Good for all ages.)