I (M24) need someone to talk about my 8 year relationship with my gf (24F). Who in my life can I talk to?

My gf and I have been dating since early high school and generally speaking we have been really healthy and communicative. A couple years back something happened where she lost a little bit of my trust (no adultery). Ever since it’s been a bit of an issue of trust and boundaries. I would like to talk to someone in my life and get some unbiased advice/input, but I don’t know who to talk to. I really don’t want to get our mutual friends involved for obvious reasons and my friends would always be biased in my favor. I’ve talked to my therapist about these issues but to be honest they have only made me even more concerned about the issues than before. Where can I go and who can I talk to about these issues?

tl;dr I need someone to talk to about relationship issues without airing out dirty laundry to friends, or getting biased opinions. Who can I go to?