Christ Centered Gamer

Those of you who have played through Undertale, would you, please, provide a bit of detail regarding the instances of homosexuality in the game? I'm unsure about letting my teenager play it, which is unfortunate, because it's my impression that Undertale provides opportunities for the exercise of virtues not usually found in gaming.
Thanks for any help.

It's been a couple of years since I played it so my memories of it are a bit hazy. There's a female character later in the game who has same sex attraction to another female character. It doesn't go any further than that.