For SO long, I've been selfless...now suddenly, I find myself with VERY selfish thoughts. What's up?

I'm 26, and ALL my life I have been the kind of person to put the happiness of others before my own. If my friends and family, those I care about, are happy, then so am I. I'm also something of a people-pleaser. I do a lot of things that probably, if I had honest free choice, I wouldn't necessarily do, just to get people to approve and feel good.

Since I was 11, I have known I wanted to get married and have children some day, even though all of my friends thought it was stupid of me to have this idea so young. Now though, at 26, a LOT of people I know are getting engaged, married or having children. I couldn't be happier for them all, but a BIG part of me is jealous. WTF??? Why am I NOW being so selfish?? What is wrong with me?

Why can't I just be happy for them, without thinking that they've "beaten" me to it?

I know a lot of the advice I will get here is to change up my social and professional circle. Only trouble is that I live and work in France (I'm English) and in a job I REALLY enjoy. I don't want to give that up just for the CHANCE of finding a relationship. Most of the people I know who are having these big life-changing events met their other half IN work, but tbh the girls in work don't really do anything for me. None of them are attractive - mostly because of their VERY immature attitudes (a LOT of the men I work with are gay, and the girls then assume we ALL are, while the ones who aren't are in relationships - mostly true, but to them, it's 100% true, which then means that those straight men who ARE single somehow don't count!).

I just need to know how to stop feeling jealous of everyone. I know I'm nowhere near that goal myself, even though it's something I've wanted all my life, but these people are my friends. How do I stop resenting them for being happy? I feel like a VERY bad person. Thank you in advance