Is It alright to be upset at my boyfriend if he..?

...Keeps undermining my arguments?

For example: I'm having a difficult time because I'm trying to figure out how to tell my father I don't want to spend every other weekend with him (parents are divorced and i see my dad every other weekend). Recently, I tried to explain to him how its not right that my father doesn't have a room for my brother and, and that we have to sleep on the couch, while my dad sleeps in the bedroom on his queen sized bed. I want him to agree with me, and support me on this, but instead he undermined me by telling me that it shouldn't be a problem since I don't see my dad very often...

It doesn't matter if I only see him that much, it still is not right that neither my brother and I have our own bedroom; and we've been dealing with this for TWO YEARS. When my boyfriend says things like that, it makes me feel like he isn't on my side, or that he doesn't understand my circumstance. He does this all the time when I go to him whenever I'm upset and CRYING my eyes out because of something my dad did, and all my boyfriend can give me are excuses for me not to be upset.

I'm sorry, but am I wrong to be so upset about this?