OK sorry for my first post being a long one, but I am in a hotel in Houston and struggling hardcore.

I am in my early forties, and for the last 5 years have been in a relationship with a woman who I love very much. But, it's been rocky. I have some major insecurity issues, and fear, and my fight or flight response is almost always flight. So when I would get in situations in our relationship where I would feel like I needed to protect myself, I would run. This happened numerous times over the 5 years. With the longest break being 8 months.

Recently when on this most recent break, and after seeing a new therapist I had some major breakthroughs, and we started seeing each other again, this time in a much more healthy manner. There was no discussion of exclusivity, it was just lets hang out and do what comes naturally. We have MAJOR chemistry. Sparks, butterflies, etc....

So one night, we had made love multiple times and she told me she loved me and wanted to be with me. But still has trust issues.

The next day, she tells me she has a date, and that she's still going on it. I was devastated. (four days after I ran)

Cut to a week later, we are talking via email, then text, then start hanging out again, and with my new found coping mechanisms etc.... it's great. I sleep over for the first time in almost a year, and we are telling each other we love each other etc.....

But she doesn't know if she can stop seeing this other guy..... we have many talks about it, it's pretty intense. I have always been a guy who prefers not to date someone who is seeing someone else. Many reasons why. Insecurities, always paramount, but also for sexual health, and just because when I am committing to date someone, I want to always give them the chance to be "the one". So today, while in her therapy session, she tells me she wants to continue seeing me, to see if she can observe my change. But she also wants to keep seeing this other guy.

I love her. And I want to be with her. But I need some help navigating this from a third party that has no involvement.

Here are my qualms.

- All it takes is one thing for him to say, and she's gone. She has five years of **** and good times with me, but none of that with him. The grass is always greener.
- Sex. How does that work? Her therapist says I have no right to ask her to let me know before she has sex with him, so we can end things, but I don't know if I am strong enough to handle that. The "not knowing" thing won[t work either because of how my brain works.
- What other nuances should I be wary of? Pitfalls? Etc....

Thanks in advance.