I don’t know what to feel

My friends are bisexual they are into girls and i can’t handle them talking about girls i’ve been there like replying to them into certain topics but I genuinely don’t like it i do it for them , for their happiness i ask about the girl she likes and care of her if she was jealous or sad of that girl and so on but i can’t handle it i get bored and depressed over it because they always talk about it and have that in common , that is ok to me i’m not against your own happiness i’m just tired and i stay silent when they talk about this certain stuff ,it has year and half since they are like this and i can’t get off my depression i feel like that is dumb reason for me ,i’m honestly starting not to know myself any more i only friend them because they like anime and manga but i never expected them to be too focused on girls . I want to die every time when i feel like this . I want help