I wish I could be someone who writes meaningless thoughts and ideas - all non-scientific- for a living...
When I look at people, many strive to find out exactly what they want to do in life.
I will do that, they say, if only they can find out what they would like to do.
The only problem is that once you are able to find the thing (you think) you want to do , then comes the following questions. Firstly, the doubts on your ability to do it, your true passion in them to do it as a life calling, and lastly the courage to leave what you have been doing for a number of years and actually trying out your chance on the one you've found.
It can be compared to finding your "true love" while being in a long-term steady relationship. You have to ask yourself, those the other person- thus the newly found love- loves you, is your passion towards that person not just some emotional swing, a fling but the real thing, and lastly can you leave the person you were with for the past years who you are confortable with and know well... can you leave it all and start over new?
It might be that you are just bored of your partner after awhile, the initial interest/passion dies out when the hormones are done with and that is why you want to try out new lovers.
Although this also may be that this person wasn't the one for you and you want/need to change/explore etc.
Again, the same with jobs... is it just that the honeymoon period is over or is it that you really need a new vocation??