What is it called when I get sexually attracted to both genders but can only be in a same-sex relationship?

The situation you're describing may align with the term "bisexual," which refers to being attracted to both genders. However, if you feel only able to engage in same-sex relationships despite being attracted to both, you might also identify as a "same-gender attracted" or "homoromantic bisexual." Ultimately, the labels you choose should reflect your personal experience and comfort.