I'm 22 M, My gf 22F & her childhood friend 23M (assume guy-X)

1)I'm an average guy from middle class family, medium build( started gym and lost around 18lbs in 2 months), shallow-minded guy(wanna be broad-minded)&dealing with my problems(changing career)

  1. My girlfriend from rich family,broad-minded & completing her studies.

3)Guy-X better and from rich family, has a well stable government job settled by his dad & In decent shape.

I'm in relationship with this girl from last year, started to know thing's about her past traumas, bond with family and friends.

So the problem I'm not able to deal right now.

So my girlfriend says she used to have feelings for her childhood friend guy-X but she was to shy to even confess her love towards him so she suppressed her feeling towards him.After partying multiple times with her & her gf's whenever that guy-X name pop's up she starts acting all weird and starts saying things are not same any more. That guy-X is really close to her sister & I have caught my gf feel jealousy against him many times whenever guy-x gets really close to her sister. Even now she has gone for a trip with her sister, guy-x & his brother. Same incident occurred today that her sister hugged guy-x in car while they all where travel & the moment them all three left the car for a site view (guy-x & his brother & her sister) she starting getting jealous & cried a little over a phone call with me & said I don't care let them do whatever they wanna do.

TDLR :- So I'm confused right now is it a red flag 🚩ahead in our relationship or how shall I deal with this situation or make her talk about this whole mess. This situation is creating mess in my thoughts process that's why I need some advice.