Now this series is a series that I really just initially got into for the girl's kissing. Because that is what this series starts out as being. The first time you watch it, you go "Oh boy, this surely must be lesbian fodder". Girls are kissing ALL OVER THE PLACE because it's apart of their worship, and it is also how they pilot their simouns (another fancy term for mech.. religious mechs)
But as you get into the series of Simoun, you realize that it's alot more complex then merely 'girl's kissing'. It's deep and weighty, it's about faith and taking chances. Yes, the main couple -is- a romantic couple, both Aeru and Nevrille, two outstanding female characters (There are alot of people who do not like Aeru, however I think that for Nevrille she is exactly what the girl needs and thus I find her absolutely delightful).
Why are all these girls kissing? It is because in the world of Simoun, all the girls are born that way. Girls.. there are no boy children. You go to a spring in order to 'become' a boy if you want to. But you are expected to go to the spring, that's all apart of growing up. Then you have heteronormative relationships based on the gender you picked (or not, the anime never says that homosexuality is a sin or not). And this series isn't all about the girls kissing, there is a really awesome heterosexual couple, and then there is the sweetest and most dear gay couple.
This series in terms of shipping has a little bit for EVERYONE. (coming from a rabid shipper, I admit by now that it is an addiction, and one that I'm likely not to cure.)
The fandom is awesome too, I mean this fandom is too cool for school. There is no hatred in their heart, they can effectively co-exist. There is no arguing over pairings and they have equal tolerance for the het, yuri and yaoi. It's a great fandom to be apart of and if you want a series in which most of the watchees are pretty nice in general then you couldn't really pick a better one!
My favorite pairings for the series are Nevrille/Aeru (the yuri), Wapourif/Morinas (the straight) and Anubituf/Guragief (the gay). Those three pretty much own my heart as to the series and I <3 it majorly.