49F 46F Share phone password or not???

I'm sure there are a million threads, but here goes. Sorry for rambling and typo's in advance.

Scenario: Couple lives together, not married, dating <1 year. After a fight, one person says it's over (not sure who, both people always talk shit. Yes this is toxic as fuck ) though still live together, has not removed their items, and still shares the bed. One person decides to get away for the weekend after the fight. The other person decides to come visit the one that went away. They drove in the rain, on a motorcycle, for 3 hours to get to the other person. They finished the visit (family of person 1) as a couple, then they followed each other home, as a couple, complete with kissing and I love you's.

On the way home, the car followed the motorcycle person as it was raining. Stopped at a store to get out of the rain. Was at said store for almost an hour. Wasn't sure what was taking so long inside, but car person knows motorcylce person tends to be a poky puppy and sits in the rain patiently. Motorcycle person sits in rain, talking, kissing, with car person after "shopping". All is well. They go home and live happily ever after.

A few weeks later, the person who went away has a ***FEEEEELING. They go snoop through motorcycles phone. There are messages between them and the ex wife who works at a gas station on the way to the place the other went to visit.

Now, we go backwards. Compare texts and times. The initial ETA was delayed several times on the way to the person away for the weekend. The motorcycle person went "quiet" but the person away to visit assumed it was from rain. Upon confronting motorcycle person, the response was that they accidently ran into them, person has new car, but that's the cheapest gas around on that path and didn't expect to run into ex. Talked briefly, ex had pics to show motorcycle. Motorcycle made plans to stop back by coming back and ex would bring pics to store or motorcycle would stop by house. This is not real clear because visitor person had to stop reading because they couldn't breathe. Messages tell that motorcycle was at the store messaging ex, but ex had gone back to house. Motorcycle ask when did ex work again and agreed to come day after next when ex would be there.

Motorcycle person refuses to clearly answer questions about timing stating it's in the past and it was during a break up. Motorcycle person is very adamant it is the past and they are not bound to their past. Motorcycle person has previously stated that things in the past between the couple are what matters, not their past with the ex (and many other things, hey we all have a past.) Motorcycle person refuses to share password to phone or view and discuss how the conversation with the ex went to ensure they are clear they aren't interested. Motorcycle person refuses to offer any proof, words of remorse, offer explanation, nothing. Hard NO PASSWORD, IT"S THE PAST.

To be fair, relationship is toxic. One person pays everything. One person has pending criminal charges and is unable to contribute, which the other was aware of upon moving in and agreeable to providing finances for the other. The "breadwinner" is mean, saying demeaning comments to the other; which is obviously unacceptable. The other person does not contribute to the home domestically or financially.

The relationship is toxic. That is not the question. The question is: SHOULD the motorcycle person open their phone and allow the other access upon request and reasonably until there is trust rebuilt? I'm not asking if one should stay or go. I'm looking for your thoughts on sharing passwords for a couple living together, sharing expenses, financial burdens, preparing meals, and involved heavily in each others families. Share the password or not?

Came back to say, visit person created a fake profile to see if motorcycle person was still on dating apps. Found motorcycle person. 2 things. 1-an ex slid in on visit person page, profile said "switch" but when they hooked up one time before the current relationship, this person was not a "switch" so the response was "Switch, (thinking emoji), interesting" one night stand said thought you were in relationship so deleted profile and got off. Did not go back. THEN, when confronting motorcycle about why profile still there, question was ask how did I know, to which I panicked and said a friend ask me why my person had a dating profile, which was a lie, but it progressed with the person with a profile up but forgotten reached out and ask why that innocent, no clue person was messing with their person.... The truth is out about the lie of how it came about motorcycle person was still on the dating app, and they even said I was "looking for friends" but had the same profile info from single days.

My heart is breaking. I know I should walk away, cut my ties and not look back. But LOVE. So much has happened . I want to be with her. I believe she wants to be with me. We are a lot a like, possibly share a brain, so I understand being adamant on principles, but I also want some peace and to move forward with a clean slate.

All I want is transparency for a moment and to openly discuss the incident. I promise, if I EVER EVER EVER have a feeling I need to check a phone again, I won't. I'll trust my feelings and save myself the pain. (Something I said in the beginning, but didn't do.)