I used to have a partner with my site and it got to be a little difficult at times. I felt like I was doing all the work and we were splitting everything 50/50. Then, he wanted to leave the site and things got a little tricky. I think the best thing to do if you are going to work with a partner is to lay everything on the table. Decide what is going to be done if one of you should leave. What kind of workload you will each be doing. Whose responsibilities are what. What will happen if both of you don’t follow through with your responsibilities. And of course, how you are going to split the profit. If you can hammer all these details out before hand I think you should not have any problems.