Dear dreaming715:
You wrote: “How do I blindly trust him after experiencing betrayal..?”- I don’t think it is possible to blindly trust after experiencing betrayal. This is why you “constantly look for red flags with (your) current boyfriend”.
Following betrayal, I think that trusting another person should be a long-term prospect, learning who the person is over time, whether the person is trustworthy or not.
Regarding your ex boyfriend, you wrote: “how did I miss the red flags?” – in your June 2017 thread, you wrote about that relationship that it lasted five years, 2009-2014. You lived with him for four out of the five years. During the last year of the relationship you were engaged and planning a wedding, including putting down a deposit on a venue and you purchasing a wedding dress. And then “we were going through a stressful time (mostly financial and health issues), but I was blind-sided when he said he didn’t want to get married anymore and wanted to leave”.
Maybe the red flag you missed was that the financial and health issues at the time required more communication with your then boyfriend, more attention to the situation, so that the two of you worked together on resolving the situation practically and emotionally.
Currently with your boyfriend, if and when a stressful situation arises (and otherwise), see to it that the two of you help each other, tackle the situation, the challenge as a team of two.
anita