Ive been dating my LTR for a few years and things have been great for the most part.

Yesterday however she brings up a guy she used to talk to a few years ago. After hours of forcing information out of her she tells me she went on a date with him years ago. The next day she then tells me (on her own) that she went on multiple dates with him but leaves out the fact that they made out multiple times (for sake of privacy I will leave out how I know that this is as far as this went). She only tells me they made out when I force the information out of her.

Her response/ reasoning for all of this is that when she saw me get so angry when she told me about them hanging out she didn’t want me to leave her, and swears this is all that happened. When I asked her for screenshots of their last conversation she was super reluctant to send them through even though they last talked years ago (apps show when messages have been deleted).

As I said before, I know that this is as far as it went but the fact that she has the audacity to lie and hide things from me does not sit right with me at all. I have demoted her to a plate but I’m willing to give her a chance based on the fact this happened a long time ago to work her way back into a serious LTR.

I’m not sure how to deal with this, the incident happened years before we started dating but the fact that she hid things from me and lied as well as excuse her inability to face consequences as not wanting to make me mad is a red flag and I’m not sure it’s worth ever being serious again. Any pointers on how to deal with this isolated yet severe incident?