My gf won't stand up for our relationship and tell her roommates that she pays the same amount or bills and its just as much her house as it is their house and she can do what she wants. Am I wrong for wanting her to stand up? I'm asking because her roommates don't want me there anymore.

Please note that your name does not appear on the lease. The house / apartment belongs to the three girls. It could be that you're over there all the time, so the other two girls feel they don't have any privacy or feel they could invite their friends over, because you are always there.

It could be you act like a jacka$$ and make them uncomfortable. It could be that you eat up everything in the house and don't replace what you've eaten.

It could be any number of reasons. If you're curious, why don't you ask them if there's something that you do or say that bothers them? One day, you could be in this same predicament so this will be good training on how to get along with everyone.

Make an effort - find out what's going on. Don't put your girlfriend in the middle of this. After all, her relationship with you could end tomorrow; she will still be stuck there until the lease runs out.

Since when is adding another person to a 3 person agreement an equal 1/3 share? She entered into an agreement with her roommates to share 1/3 of the space, expenses and rent .. Adding you as a full time guest is stepping outside of the boundaries of the agreement.  If they are not in agreement of making a change to the original agreement,  by adding you as a fourth  person, or even recalculating rent and expenses for four people instead of three...that is their prerogative. She has no right to force them to accept it...it is a negotiation. 

.. And NO she can not just do as she pleases ... What ever gave you that impression.  What she wants will have to be negotiated with her room mates. They have a say in what transpires under that roof .. Not just her, and certainly not you.

This is about legal commitments made .. A contract .. This has nothing to do with her not stepping up to defend your relationship.  If you want to move in with her, then renegotiate her lease with her roomies or buy out her lease and find a place of your own where you two can co-reside.

While she has an "equal share" in the house ... Her roommates' right to feel safe in their home overrides her right to have you over.  So you need to figure out WHY they don't want you over, and address their concerns.

If you are living there, you should pay a part of the bills.  She doesn't have the right to let another person move in, even if it is just in her room.  If you are taking a shower there more than once a week, chip in for the bills.  If they don't want you there, she can just get an apartment on her own.

I had roommate whose unemployed bf just moved in.  His stuff (surfboard, etc.) was all over the house.  He was in the shower when I was trying to get ready for school.  He was always downstairs loafing around.  The other two of us eventually kicked her and Mr. Lazy out.