Neptune opposite Venus aspect in the relationship astrology indicates that you two met in a time that you were both longing for a perfect mate. If you can still recall the moment before you met each other, you were very unrealistic about how you want to experience true love. You are an idealist a person who is in love with the idea of love, but does not quite understand what love actually means in reality. Maybe you dreamt about being the princess in a fairy tale, or the knight in shining armor who will rescue a damsel in distress. A fantasy that is perfect enough to get you satisfied, and for you to say that he or she is the right one for you.
Neptune opposite Venus in the Synastry is tricky because it lets you live up with your illusions of love, and at the same time experience real love. The love is strong enough to change how you understand love itself in a realistic view. There are times especially during the second phase of the relationship where your dreams fade away, and the negative aspect of Neptune opposite Venus is taking place. You are slowly realizing that everything you believed before entering that particular relationship is a false impression. You will surely feel betrayed by your own imagination though deception is quite hurtful you cannot leave your partner because you already fell hard for him or her. The reason you are experiencing this aspect so that you could help yourself to turn away from your illusions of a fulfilling relationship.
When both of you overcome this aspect, you two will finally achieve a higher form of love that is emotionally satisfying, and enduring. You will become more sensible when it comes to giving and receiving love. The knight in shining armor (as discussed earlier) may realize that he also needs to save himself in order for both of them to survive, and as for the princess she may decide to focus on her self-worth so she will not depend on the prince much. The process is difficult, and not all people with this experience learn the lessons of Neptune opposite Venus. Most of them end up with an embarrassing breakup because of their perfectionist attitude.