The j2 dynamic has changed drastically hasn’t it? Wow they give off some really off and sour vibes. Never thought it’ll get this bad.
Honestly I don't think so.
Firstly, everyone needs to understand one thing that whatever we see on social media is not the true reflection of celebrity private life. Infact it is not the true reflection of anybody private life, we choose what to post on social media. So to make assumption solely on basis of social media I'd not accurate. There are lot of other factors to come into play.
Now to your question of if the J2 dynamic has changed drastically and gone sour. Then, as I said I don't think it has. The way I see it, the friendship has adapted to next step in J2's life. Again fans don't understand that until last year, J2 spent almost every waking moment together (figuratively, not as partners). So it made sense for them to do things together as they were on same schedule and the fact that genuinely love spending time with each other helped. So, staying in same vicinity + being on same scheduled help them to spend holidays and birthdays together.
Now things have changed with their schedule. Both have different projects in different place at different time. Jared was lucky enough to shot a show in his town. Jensen couldn't so he did the next best thing that is to shift where his show is being shot. No one knows if its temp situation or permanent. So, now J2 are not only in different show with different schedules but also in different city. Unlike before their wives and kids can't spend time together. Now you might think he could let Danneel and kid be in Austin. Then, again I think Jensen needed them to be their with him solely cause he was entering a new territory. SPN was second home to J2 so they were comfortable their, with other project they might take time to get to that level or they might never. No one knows. Moreover, now J2 needs to shed their image of being a single unit and build an image of an individuals. So instead of being together, being alone in public eye will help.
That is why we dont see J2 together every waking moment that doesn't mean they aren't friends anymore. Friendship is a strong bond, now, J2 friendship is more private then public. The prying eyes have lessened they don't feel the need to air everything on social media.
None of us speak to our bffs on Instagram or Twitter or Facebook. if we want to share anything all we do is whatsapp or call the person. And, if the schedule match and their is a free time we meet. I went to India this Christmas and I was able to meet my BFF who live two buildings apart only after three days. It wasn't because we hate each other but because we both had prior commitments, I had my over excited family and my BFF had her job. But when we met on 3rd day it was as if nothing has changed, we spoke about anything and everything's and just spend the entire day together. I didn't feel the need to post that meet on Instagram or Twitter coz those feelings were personal. Same is with J2, now that they are on different zones meetings are difficult but that doesn't mean there is no conversations happening.
Also, this question arised because of recent seperate vacation J2 took for Christmas and New Year. I don't understand, people behave like J2 spend every vacation together. I don't think that is true, if you avoid tinhat theories and look into their timelines. Jared & Family have always went to different cities for vacation. The only vacation that people know J2 took together was that of Turks and Caicos, rest all have been individual vacations. So I don't understand on what basis people think their relationship has changed or freaking out on seperate vacation.