Hi and Welcome!
I forget who said it (maybe RP?) but something about not really getting to pick your metamours or your lover's lovers. It's hard when you don't connect with some one that your SO really cares for. I know my SO's wife and I had a bit of a difficult time connecting, she's pretty quiet. We're finally getting there I think. Some relationships enforce a veto power in partner choice. It's not easy though when you both don't connect. But from what I've seen, that's not uncommon, esp. in V's and Triads to not all connect equally. I think it's like super good luck when you all just click. Seems to be rare. I'm pretty tired though, not sure what I'm getting at, so I'm signing off, but good luck!