I've had folks say similar things to me about my W. I just hold on to the fact that I fell in love with my W for a reason and that we were good for a long time for a reason. Things got bad because we didn't focus on each other. If we both put in the effort, things could be better than ever. All that said, I have the same question as you -- trust. On the one hand, it is an effort of will. You have to decide to trust. That's what I did with my W after the A. I could either drive myself nuts that she was still seeing him or let it go. I let it go. Beyond that, I'm actually more concerned about emotional trust. How can I ever trust again, were we to make another go, that she'd be emotionally honest with me and tell me her issues/problems? To that question, which is the one that I think you're really asking, is that I have no answer. I guess it'll be doing the small things well over time and a "feeling" of closeness. I do know/understand from reading that it will take time, so if you and your W do start making a new beginning, don't beat yourself up for not totally trusting her immediately. It will take time. Beyond that, can't offer anything else.
Back to the things that friends noticed that you didn't. Those are the reasons you're here. Your next R, with W or without, is going to be better because you better understand what it is you want and are looking for/willing to put up.
BD
My latest
Me: 36 W: 35 2 D: 9 and 5 T: 16 years M: 12 10/4/06: Bomb 10/5/06: Ended A 4/22/07: ILYBNILWY