Is it really hard to be transparent about what we feel?

Problem/Goal: Help her to be able to be more open with me.

Context: Me (m24) and my gf (25) were talking thru phone bago sana matulog. Maayos naman yung usapat, but the mood changed nung nasabi ko na mag aattend ako ng wake with my guy friends kasi namatayan yung isa naming female friend. When I asked her why, she told me kasi naiinis daw sya sa guy friends ko. I was shook kasi nakakasama ni gf yung mga tao na yon before she flew abroad. So i asked her why, to where she replied with "inaantok nako matutulog nako, kung may sasabihin ka chat mo nalang." And the call ended. Nag msg ako right after saying na i dont mind if ma hhurt ako sa opinion nya abt my friends, kasi if nasabi nya yon it means may visible sa perspective nya na mali, na unfortunately, diko pa napapansin na baka need nga ayusin. And that I value her opinion more as my partner, keysa sa opinion ng iba kaya i asked her na sabihin sakin. To which she responded "dapat alam mo na yon." Nung sinabi ko naman na "what if hindi ko talaga ma distinguish?" Bigla nyang binawi na di naman sya naiinis sa friends ko, sakin lang daw. And after non, nag sabi na sya matutulog na talaga sya

Previous Attempts: For the longest time, since we started our relationship, i was really insistent na we should always be transparent abt everything, to which she agreed. Pero there are times pa din na she would opt not to tell me about what she feels saying "okay nako, wag na natin pag usapan." I've been leading by example when it comes to being honest and transparent about what I feel, pero di pa rin talaga nawawala sakanya yung "wag mokong tanungin, alam mo na dapat yan." I really would like her to open up, especially abt the things that makes her uncomfy kasi I'd like to understand her more that I do now. Although i know it's unhealthy for her to keep things about our relationship to herself, pero i still want to guide her w/o making her feel na "im better than you."