She had Pisces rising which is ruled by Neptune and Jupiter. Venus also rules her ascendant by exaltation and Venus forms an almost exact square to Neptune in the unfortunate 6/8 houses of her chart. Neptune is the most elevated planet in her chart, giving it extra prominence in her life along with it's ruling her Ascendant.
Venus square Neptune by itself indicates a potential to over idealize relationships, be very spiritual and creative. She would have trouble
picking a suitable partner as Neptune clouds one's perceptions of a loved one. This may also indicate that she might experiment sexually by being homosexual or bisexual. Since both planets are so strongly connected to her life (ascendant) they showed the struggles that she would endure with relationships and drug use. 
In this article I will be discussing transiting Neptune and how it triggered, along with other planets, major events in her life. In her particular chart, Neptune's transits were very powerful and indicated life changing events, good and bad.
- 1985 - Neptune enters the sign Capricorn ( 0-1 degree)
Here Neptune was traveling through her career area of her chart and forming positive aspects to her ascendant which resulted in her becoming famous all over the world.
- 1989: Neptune was at 10 degrees Capricorn:
All together, this was an overdose of Neptune influence at the time she met Bobby Brown. They were both successful singers who had the potential of creating amazing music together and/or raising a family of more talented and successful artists.
- July 18, 1992. After a three-year courtship, Whitney and Bobby married. Neptune 17 Capricorn.
- On March 4, 1993, Houston gave birth to their daughter Bobbi Kristina Houston Brown, her only child, and his fourth. Neptune 20 Capricorn
- Early 2004 - Filming of her husband's show which she starred in "Being Bobby Brown" Neptune 11-15 degrees of Aquarius
- September 2006, After years of controversy and turmoil, Houston separated from Bobby Brown filing for divorce the following month. The divorce was finalized on April 24, 2007, with Houston granted custody of the couple's daughter
Neptune conjunct Saturn caused her to seek rehab for her addictions. Saturn brings isolation and structure to the Neptune influence of wanting to escape in drugs. This was a positive time for creativity, song writing and just establishing her dreams into reality.
- February 11, 2012 Whitney's death.
Neptune in Pisces with Pisces rising most likely gave her some powerful psychic perceptions along with a stronger desire to escape the harsh realities of this life.
R.I.P. Whitney Elizabeth Houston
[1]https://en.wikipedia.org/wiki/Whitney_Houston