girlfriend acting strange sometimes

My girlfriend sometimes puzzles me. today she cancelled a meeting with me and said she has to meet with her friend (who she despises) and her friends bf. apparently she needed to interview him for work. i didn't say anything and spent the time going to the gym and working on car. last week she also wanted me to go with her to friends birthday (she hates them too) but i declined because i thought she didn't really want to go, but she did, so she went without me. she was also very edgy when i was on her phone fixing her sim card issue. i trust her and she's been a very respectful and faithful girl. i'm not sure if i should be concerned but a friend of mine said these are red flags. any suggestions what i should or shouldn't do?

potential red flags yes - but not conclusive evidence.

with females.. yo ucan't take their word straight up. females never tell you exactly what's goign on. so when they say "i hate her" it doesn't mean the same thing as when a man says "i hate him". they just work a whole lot differently. so dont' take her words straight up.. watch her actions. (yes females can attend and invite each other to events that they don't particularly like.. they do it for other reasons which i may not necessariily know all of them, but won't get into the reasons i thin i know they do it).

if it's alwya sconfusing and you're always on eggshells - then you may want to cut bait here. but to your specific question - i don't see any evidence to make me feel conclusively she is cheating.

Ask her and look at the response