<human>: Can you provide a brief rundown of the text in within 3 sentences?

gf is 17, I (M) am also 17
So my gf of 8 months recently proposed the idea of having a threesome.(Just to clarify this won't involve sex. We have both agreed to wait for that) 

She didn't offer any details or say who with, just that she was interested in the idea of having one. We have been mostly solid except for the occasional minor argument, with one rough patch which we worked through together. 

Anyway, I'm not totally sure if I want to go through with it. I quite strongly believe in monogamy. I don't know the potential repercussions it could have on our relationship, or of we will be totally fine afterwards. 

The idea does appeal to me because I'm a horny teenager, and my instincts tell me we will be ok as a couple afterwards. I would just like some second opinions on it.
<bot>: gf propsed the idea of a threesome, i think im ok wiht it but im not totally sure.