Do lesbians involved in a relationship get their periods at the same time as the other woman?

I have been in relationships with women for over 13 years, and lived in a house full of girls when I was in college. Every time, all of us synched up in pur cycles. This theory even held true to other women I worked with. It's not a lesbian thing, it's a pheromone thing. However, I have been exclusively with the same woman for over 4 years now and NOT ONCE has our period synced up. It has actually made me irregular and our cycles seem to be chasing each other with no success...