in addition to not caring much for some of the tropes involved and thinking they're boring - you're already fighting against the predictability of pairing 'the main boy' and 'the main girl', the visions make it feel too 'soulmates' for my taste, and I suspect it will play into the trope a traumatised bad boy having his pain healed by the embrace of the most beautiful woman in the world, which I find cliché and tired - I also find most fan material mischaracterises them, particularly Jon. As I mentioned in more depth in that link, I find purely sweet, loving, and romantic depictions of incest fundamentally dishonest (and this is what 99% of the fan material is), but also a lot of material, even that purporting to be book accurate, depicts Jon as a spineless doormat who will do anything for his queen when in fact a key facet of their relationship will be that it is between equals. Indeed, Jon pretty famously is stubborn when it comes to his principles, even refusing to budge for the likes of Stannis Baratheon - who outranks him and has far more leverage over him in ADWD. Jon also has such a fraught and complex relationship with his own desires because of his vows and the shame he has internalised, so I can't see him being instantly down bad for anyone, or having his head immediately turned by a pretty woman - he's not that shallow, and is too busy with his job, it'll be slower and even begrudging. even once he and Dany enter a relationship, he'll probably continue to bicker with her over the war and refuse to concede on certain issues. in fact one of my favourite things about Jon is that he's someone principled who tries to do the right thing even in very complex situations, so when people undermine this aspect of his character I do just get annoyed. lastly, in terms of Dany, I also think some of the content emphasises Dany's beauty over any of her actually interesting and unique qualities and thus it loses me. in narrative, beauty is boring to me unless its psychological impact is explored, but more than that, as an adult who likes to read broadly, the last thing I care about is that these teenage children are conventionally attractive, actually.
usually I would ignore fan canon and turn to the text itself if I found other fan interpretations annoying, but the lack of canonical interaction between Jon and Dany means that you're much more reliant on fan interpretations than normal. I try not to reflexively hate something if it's popular (and I do like popular things if they appeal: I love Jaime and Brienne and that's very popular), but the fact that this ship, which is often built upon fan interpretations I dislike, is so popular and is unavoidable in fan spaces and often saturates tags, doesn't exactly help.
