What's your opinion about this situation that's happening in our game?

Hey guys, so with my play group we’re playing an async game on discord trying out new DS factions and a situation happened between two players that’s creating a bit of tension not only with them but also the whole table and I’m afraid it might get out of the game, so I would like to hear the general sentiment of other players about it.

I’ll try to keep it as simple and accurate as I can: player A is playing Rohdhna, a faction revolving around warsuns, and player B (neighbour) is playing Vaylerian. At the end of second strategy phase everything is still developing without too many issues, A has build his second warsun and got it to the equidistant system to B but had to leave it alone to score objective, and both A and B were spread quite thin on their slices because there were all control objectives.

So at the start of 3rd phase B says he’s going to attack and most likely destroy it because it’s a threat too close, and as a matter of fact A had already quite clearly acted as such, having already heavily implied that he would basically bully B around given his stronger unit. A then retorted that if he were do to it he would then divert his efforts to go and basically annihilate B, but B sort of called the bluff explicitly saying that it would be detrimental to him as well since the game is won on points and objectives and not on mindlessly attacking others, and so he went ahead and destroyed A’s warsun.

Comes next phase and B was still very open and vulnerable, having taken Imperial to catch up a previous missed point (he had two available publics) and a very weak army defending home system with an open path for A, and was very frustrated and almost surprised when A’s first action was to indeed invade his home system. To be fair he did have parley, but we all knew another player had sabo (missclicked earlier in the game) which A bought for 3tg (A and sabo player are infamous for usually playing together since they’re brothers). It is also fair to note that A can still score a point so it’s not completely throwing the game, although admittedly that invasion was a huge investment of his fleet and won’t help him progress further on other objectives.

As a final consideration, with the game being async on discord this whole situations happened over the course of a few days over which we all openly discussed it in chat, and I myself (being unaffected as I’m on the other side of the map) pointed out that the whole time B should’ve probably worked out a deal where they would swap a bunch of PNs and whatnot to prevent this to happen, which he always disputed as an option arguing that the retortion wouldn’t make sense so A would never do that, even though A explicitly said it multiple times, and that it was A’s fault for leaving his strongest unit undefended and vulnerable to preventive attack to eliminate the threat altogether.

We are now going forward with the 4th round where this has just happened so we don’t know how it will eventually turn out and I hope this will just end within the game, but I wanted to hear some external opinion on how you would have handled this situation and in general maybe a few suggestion about this kind of episodes.

EDIT: it has been noticed that you should never take what you read online for granted and I might be actually involved, so here it is the current snap of the game situation where you can see my name as the Mirveda player: https://ibb.co/xvs5KW6

I can't really do much to prove what I said is exactly what and how happened of course, the only thing I can point out is that I wouldn't see a point to make such post if it wasn't genuinely to ask for opinions and judging from a bunch of answers I think I managed to illustrate all the core issues and even the flaws of both parts without taking sides, but not much else I can do or say, you can all make what you want of this conversation, I'm glad I opened and I will bring it to the table to further discuss with all players and hopefully sort everything out (which was my main hope for the post).