I get it but I don't know I just never been put in that type of situation so it's hard to understand how someone can leave a good friend behind for a relationship that may or may not last.
I could understand if they were married but they just started getting serious in about two weeks.
Generally the opposite sex friendships i see that actually work without complications have matching marital statuses.
IE: You married, and your female friend is also married, and your wife and her husband also aquantainted and the four of you hang out together
Or alternatively , you both single but just friends.
When you have a girlfriend you should be including her in your social circle anyway, The main reasoning for hanging out with your guy friends without her is because you have different interests girls aren't usually into,
But if you are doing things men and women enjoy, why not bring her along anyway?
however if the girl you hang out with is just a butch tomboy/stud type who enjoys doing male activities more than female ones, usually people don't have a problem with her being one of your bros anyway.
Its pretty easy to figure out if the optics look weird or not. Like i said at that point its just up to you to decide if you care enough about your partner to acknowledge those optics or if you just gonna let that be her problem.