In French, it's "partenaire" either way, which makes it surprisingly neutral in a language where almost every word or object has an assigned gender. However, other words around it (like my partner, your partner or the partner) are themselves gendered, and therefore give away the gender of the partner in question.

I love how in Norwegian the word for boyfriend or girlfriend is"kjæreste", which just means "dearest". All you need to know it's how dear this person is too them - the dearest!

Oh, a fellow slav-language enjoyer it seems. I tip my hat to your courage for using that form, for even the seemingly default male-gendered word causes eyerolls around me, not to say about something more rad.