I normally talk to Shadowheart first, agree to meet her later and then suddendly everyone tells me what could have happened, if I had picked them - even if they wouldn't have offered, if I had talked to them first (I did try it once with reloads, to see, what would happen, after everyone said, what I would miss to not pick them).
Might be this, because I don't try anything with Shadowheart, so I haven't gotten any jealousy scenes.
I have only romanced Astarion. I did try Gale, but despite him having a exceedingly high friendship with Tav, we just share wine together. Never got the Weave Scene.
It's quite funny, because I did try Gale's romance once out of curiosity, since it was so famously buggy, and ever since his dialogues keep bugging out in my other runs.
If you want to try, you basically have to camp at every approval increase until you exhaust all of his conversations. The issue is that other companions seem to take priority, so you need to really rest spam, or travel just with Gale. But because his approval is very easy to get if you do good deeds at the grove, you can actually get the weave scene very early on.
