My girlfriend lives with me she is 100% dependent on me, but we are not married is she considered my spouse? Does it make a difference that we are lesbians?

[rjs]

Your girlfriend is not your spouse unless you are legally married. It doesn't matter that you live together. It doesn't matter that she is dependent on you. It doesn't matter that you are lesbians. She is not your spouse unless you are legally married.

[xmasbaby0]

If you are not legally married then your GF is not your spouse.  She might meet the criteria to be claimed as your dependent for the $500 credit for other dependents, but you cannot file a joint tax return with someone to whom you are not married.

https://ttlc.intuit.com/questions/4499708-what-is-the-500-credit-for-other-dependents-family-tax-cre...