Question about astrology/synastry. I can't find the answer!

[amitten]

I was doing some synastry comparisons with my chart and that of a guy I just started dating.

Question: When comparing planets in charts, do they "cancel" each other out? Like this:

My Venus is sextile his Mars. However, HIS Venus is square my Mars. One is good and one is apparently bad. How do I read this, then? That is just one example--there are several planetary aspects where if I am the A chart and he is the B, it's glorious. But if he is the A chart and I am the B, it's gloomy. Which one do I read?

I have tried to Google this question and can't find an answer.