It creates divided loyalties… who or what will they put first? What will best meet a given friend's own needs and goals -- their friendship with me, or their own other-community acceptance by peers there?
It is hard for me to assess trustworthiness in real-time, anyway, and if there are conflicting loyalties surrounding a friend or sweetie… I almost *have* to be somewhat guarded around them. Since I can't be sure which way they will go, and am bad at assessing their attitudes. I grew up with lots of cases of professed "friends" who I would trust, and then they would betray me to gain brownie points with a given social circle's leadership. And this still happens to me, occasionally, with friends or even sweeties.
Over time, this dynamic of guardedness on my part, and being caught-in-the-middle on their part, seems corrosive to the underlying friendships where it has occurred. Eventually, if the feud with the community leaders and I isn't cleared or settled, I find myself distancing from or letting go of connections with most or all of the other community members. The ambiguity, structural conflict of interest, and conflicted loyalties is not conducive to growing and strengthening connections.