Looking for advice!! 

I currently attend Columbia University School of Social Work for my master's program. One of the requirements for this master program is to have a practicum placement, which is essentially an internship to receive real life experience in a social work site affiliated with the university. Three weeks ago, I interviewed at a placement (I will keep it anonymous) and I told the interviewer, who is also the founder, about my full-time work schedule, particularly I would only be available during the week in evenings and during the day to afternoon during the weekends. The next day, I received an offer letter from him, and I accepted it. Before I go further, I need to point out that the interviewer is also the founder who is also the supervisor for me. (There is no hierarchy, it's a one-man organization). Fast forward to last Wednesday, I communicated with him about an assignment that was due for the university. A part of this assignment was specifying when I would be working on the assigned task designated to me through the internship and this needed to be agreed to by him. I wrote that I would be doing most of the work during the week in evenings and on the weekends in the morning to afternoons, the same preferences I stated during my interview with him. We met on Saturday to discuss this further, and he told me that my availability did not work with his because 1) he was only available during the week on Mondays, Tuesdays, and Wednesdays after 3 pm to 5 pm and then again after 8 pm and 2) on the weekends he would have to travel overseas for business and have personal time. I tried to make it work, saying I was willing to hold any meetings during his schedule, work on some of the tasks during the week such as seeing clients, and then working on research related work during the weekends. I didn't know I got terminated until after the meeting in which he sent a formal email to the practicum director that I was cc in. He even gave me a task to complete within a week's deadline before the meeting ended.

I'm curious to know if I can take any actions against him. I feel blind-sided because I literally made my availabilities clear to him during the interview and I got an offer letter afterwards. Why give me an offer if you knew ahead of time you wouldn't be available on the weekends and have a limited schedule during the week, essentially, not being considerate that our schedules didn't match. He literally terminated me for personal reasons because I did nothing wrong, in terms of ethics, boundaries, or lack of performance. I spoke to the practicum director in the university about it and he literally said it was still my fault. I don't think the university will do anything about this, but what can I do? Is it really my fault as a student?