Life's phases

So today I open my Facebook news feed, and the first thing I see is that one of my old fellow biology students got engaged to her boyfriend. Last Saturday, I discovered that the first boyfriend I ever had (I was 16) had gotten married to his girlfriend of 8 years. A week before that, an old friend with whom I've lost contact also married, and he (well, his wife) is expecting his first child soon. I know of 2 other upcoming weddings this summer, one of which I'm actually invited to.
See a pattern emerging? I certainly do! Somehow, I now find myself in the "getting married" life stage. A few of my friends jumped the gun on this one, and are already in the "buying the first house" stage, while some are taking the "first child" stage a bit early (see above), and some can't be bothered about marriage anyway, but on the whole, most of the long-lasting relationships around us are getting married. How did this suddenly happen?
For me, it is kinda strange, because my friends can be divided along 2 lines: those I know from secondary school and my first study, who are all roughly 25-30, and those who I know from my second study, who are all roughly 20-25. The second group are mostly still students, busy moving out of their student rooms and getting their first rental houses, busy finding the perfect partner or thinking up what they actually want to do with their lives. The first group has got that pretty much covered, most of them already have permanent jobs (some of them own their own companies!) and houses, and are now ready for The Next Step. I somehow find myself in between these groups; I'm still studying, but also already working quite a lot and my boyfriend has a steady job, we've already lived in our own rental home for almost 4 years now, but are clearly not doing any of the Next Step stuff, because hey, it's a bit early isn't it?
I wouldn't say it's freaking me out, or letting me feel that I'm 'behind' (or 'ahead', for that matter), but it makes me think. People tend to move in packs, and apparently I can't decide whether I'm going to go early into the next stage, or linger around a bit in a stage that most of my friends have already left behind. This won't last much longer, I can tell you, because in half a year I will be finished and I will (hopefully) be working, and then we will also find ourselves in the "hey, suddenly I've got all this money, let's do something with it!" stage that you get between finishing your studies and getting children (clearly, I have no experience with this myself, but some of my cousins (with young children) sigh at my imagined freedom and financial wealth to come. But then they all waited until they were 35 before they had their first child, and that's not something I want to do. Oh dear, seems like I'll be jumping some stages ahead too...)
In a couple of years time, we will all be having children together (not literally...), and then the talk will be about schools and how difficult it is to combine babies and work and then how difficult it is to combine all you children's hobbies, and then we will all be having raving adolescents and mid-life crises and divorces together, and then... It feels like a drag, really, like something you can't escape. Technically not true, but you see it in groups all around you; once one starts getting married, all of them do; once one couple has a baby, all of them want one too, etc etc... (apart from the one "drop-out friend" that most groups have, the one who still lives in the fabulous apartment in the city centre and can't be bothered to tie themselves down to one specific job or partner, but I don't see myself taking on that role, and I have several friends who qualify for it already).
All in all, I'm very happy to have some 'younger' friends who tell me that I'm crazy to already be thinking about stuff like this, because they're going to study abroad for two years, and why shouldn't I?