They aren't, they havent since the early 2000's it has been an afterthought that's why it is on the sorry state it currently is.
The only thing Jean has showed so far is teasing Wolverine, maybe, just maybe she is also doing cyclops but then again that is still not pushing because that along with emma causes more damage. It is as if someone wrote a story screwing over a relationship and say it is being pushed.
If anything they are pushing the poly ship without really caring about any character or relationship involved. And maybe some people don't like (i don't) but others do and that's what marvel has decided to explore, they are reaching to the people who want to see that.
This is all fictional anyway. People love, break up and do stuff just to sell monthly funny books, not because it makes sense or has a deep meaning or anything like that.