I think it's fair to say that you're not alone.
A 2013 report by the New Economics Foundation concluded that working shorter hours would leave people better able to balance their work and personal commitments, and ultimately be happier. A working week of around 30 hours was proposed as the ideal to shoot for, although others have argued that 21 hours a week is the ideal number.
At the same time, a study shows that you're probably only productive for around 3 hours a day.
It's bad in a sense that it sucks and it definitely effects one's morale to be attempting to work when simply not having the focus to do so. Some people may find it easier than others to get through the day when surpassing the ideal number of working hours
The number of working hours have already been reduced from ~60 hours in the early 1900s to ~40-44 today, depending on which numbers we're looking at. Some countries are looking at reducing the number of working hours down to 35 hours and France is an example of one that already has implemented the 35 hour work-week.
We can draw the conclusion that it's only normal for you to not wanting to work long hours but then we come to the latter part of your question. Some people, extroverts, have a constant need to be doing something. Social events can be one example of such things.
If you don't fall into that category its only normal for you to not wanting to do those things. Many people never show up for events outside work and they do fine within the workplace. You may decide to balance this and perhaps show up and leave very early, but in the end your feeling is only natural. I don't have any research to back this up at the moment but I've have been lectured somewhat on the difference between introverts and extroverts and how different scenarios effect them.
You may wish to become a contractor to control your hours more freely or try to break the workday up by getting small rests or have a little bit of fun, for example by reading a short article on a topic that you're interested in, if you feel like it helps you get through the day and perhaps results in more production overall.
You might wish to consider finding another job where you're more interested in the projects at hand in the end as it helps with focus up to a certain degree but of the day you have to realize that there's only so much the human mind can handle and it thrives in different scenarios depending on who you are. There's nothing wrong with you for sure.
If you're being forced to work way beyond what we already consider rather absurd you need to decide whether that's a life you wish to live or not, but it's definitely not healthy and will probably result in burnouts.
Conclusion: it's bad in a sense that it sucks, but it's only normal to feel the way you're feel. How you adapt to the situation is up to you.