In many cases you can have both X and Y, eg. if X is camping and Y is hackathons, go camping one weekend and go to the hackathon the next weekend (or have one partner go camping and the other go hacking, if you value the individual activities more than the time spent together). If X is a clean apartment and Y is more time spent programming, throw money at the problem and hire a cleaning lady. My wife and I had a fight early on in our relationship over whether the Brita should be cold or lukewarm, and we solved it by buying a $1.50 pitcher, putting my drinking water in the fridge, and putting hers on the kitchen counter. Or for a more complex example, if X is kids and Y is a startup, you figure out what else needs to change in your life to accommodate both (eg. pay money for childcare, set boundaries on work time, babysit the kid while answering support emails so your partner can take him when you have to do customer site visits) and make it happen.
There are some issues that really are mutually exclusive, mostly because they cut to the heart of what a relationship is. If one partner wants kids and the other wants no-kids, there isn't really a way to resolve that and still have what people would consider a marriage. If one partner wants to live on a farm but the other wants to live in the city, or one is a neat-freak and the other is a compulsive hoarder, you're headed for problems. If one wants the kids raised as Orthodox Jews and the other wants them to be fundamentalist Christians, this is probably insoluble within the conventional definitions of those religions. These are beliefs where you really want to make sure you match before you get married.
But even a lot of things that look totally contradictory at first can have solutions if you're willing to give up other stuff. I know couples that live in different cities and only see each other on weekends, or ones of different religions where they've just decided to mash their different cultures together and create their own religion for the kids.
There are some issues that really are mutually exclusive, mostly because they cut to the heart of what a relationship is. If one partner wants kids and the other wants no-kids, there isn't really a way to resolve that and still have what people would consider a marriage. If one partner wants to live on a farm but the other wants to live in the city, or one is a neat-freak and the other is a compulsive hoarder, you're headed for problems. If one wants the kids raised as Orthodox Jews and the other wants them to be fundamentalist Christians, this is probably insoluble within the conventional definitions of those religions. These are beliefs where you really want to make sure you match before you get married.
But even a lot of things that look totally contradictory at first can have solutions if you're willing to give up other stuff. I know couples that live in different cities and only see each other on weekends, or ones of different religions where they've just decided to mash their different cultures together and create their own religion for the kids.