The bubble isnt the problem. Since we dont often hang out with anyone beside each other I dont want my S.O to feel jealous or left out of this new friendship. Is that weird?
If your S.O is feeling jealous, then you may need to have a wee talk about the fact that, a) You’re not interested in this person romantically and, b) that being jealous over a potential new friendship is kind of possessive.
I’d encourage you all hang out together for starters, I think that would build some trust amongst the three of you.
To eventually answer your question though, considering your partners feelings isn’t weird at all.