Should She Stay or Try to Save the Friendship?

Two of my oldest, dearest friends, [40M] and [40F], have been dating for about a year. She trusted him fully and has always thought he was a really great guy. They have seen each other get married and been at their kids important events throughout the years. Her husband died unexpectedly and he was a listening ear (he's divorced). Nothing more and neither of them, in a million years, thought that they would be so compatible. So they talked more and more. He knew her insecurities and things she had learned from past relationships. They never thought they would see each other in a romantic light but as they began to spend more time together, it was naturally a perfect fit. She had never felt so safe and loved. He made her feel like he couldn't believe what he had attained and made comments about how happy he wants to make her always.  He was very single before this with no plans to settle down until she showed up and he enjoyed talking to girls. Friends, chats, online dating... wherever he could find some companionship. They had several conversations regarding these connections, and she made it clear that she was not doing that and did not want to be with someone who does. If he wants to continue with that, she can accept that and move on. He said he doesnt need that and wants her.

There are a couple of girls he is really having trouble letting go of. A previous girlfriend and another that might as well be. The first he keeps trying to sneak off to and the second, he does at least a few times... maybe even once a week while in a relationship with her. When she see messages between them, they always have explicit context and/or conversation.

So... they are 5 months into the relationship. They get away to this super secluded cabin with a hot tub and enjoy each other for a couple of days and returned the day before Thanksgiving. That night she had enjoyed their time so much, she wanted to try to video chat and see where it led. Every sexy text was met with a short response and she could see he was online, not for sure, but likely chatting with someone else. Alarms were going off in her head. So, she looked up her address, got in her car, and headed that way....

[Y'all she is not a crazy girl. She wants to do her thing and let you do yours... because she trusts that you will not disrespect her. And of all men, she thought he had enough respect to be honest about what he wanted and for sure not do her like that. She had given him the option to walk away and do what he wanted with who he wanted.]

As she turned the corner, there was his car in her driveway! She started to leave a note and drive away but he came out as she was walking toward it. He was of course surprised and acted as though he was doing nothing wrong. They both left from there and headed back to his house to talk. He told her it was nothing and that people go just to hang out and smoke there all the time. He understood why she upset her and said he wouldn't engage with her anymore. This is not the first time this one has been an issue,  remember. The next night she saw messages between them from the night she found him there. A video call that was not short AND during the time she had been trying to have a video call... and several messages about how he didn't cum, she wanted to make him cum, and THEN messages that he was coming over now and for her to keep that same energy.

So they talked about it again...

The connection and chemistry is amazing. I don't doubt that he loves her for a second. He did not anticipate having this relationship and she has been understanding and patient with this issue. Even after this event... he has messaged her after not having a car for a few weeks and she stated that she was so excited. She don't think they had gone that long without seeing each other since they met... those were in January :/

He has also deleted many messages from a specific female friend over and over again. He has asked a friend to lie and say he was home when following an ex around (and texted me asking instead), hidden visiting another female friend late at night (and in her car). She asked him if he went anywhere on this one and he said 'no' and she had to tell him that she knew before he admitted it.

Now, she has trust issues and has asked for more transparency. He has given it, and then taken some back, and given some again.  Anytime she doesn't get it though, even in the smallest way, it feels like he cannot understand how he hurt her, or he would be sure to be transparent every time. She is also very frustrated because SHE DOES NOT want to be that girl, having him tell her who's talking to him or whose house he's going to.

She's said she always thought a lot of him, just as a person. He is awesome and he does love her. Her late husband (of 17 years) was also awesome and loved her, but she learned some things too. She doesn't want to spend her life with someone who does not respect her every second, and consider her before every choice. If she can't have that, she doesn't want the relationship. She DOES want them to be friends if they can't be more.

She has shared her concerns and insecurities, she has asked for what she needs after missteps, and when promises were broken... she has TOLD him what she needs... she feels like he doesn't understand what he did to her. If he did, these things, even small things, like responding to a new girl in his TikTok chats would be an automatic no from him or he would be sure she knows before he goes that he is going to visit a female friend late at night. It's like he is doing it to her all over again.

What would you do?