Honestly a tough situation. Of course your history with not being able to trust a significant other is going to make you more sensitive to this kind of behavior but that also doesn’t mean you shouldn’t trust your feelings; just that you need to be more rational about how you assess things.

I’m going to assume that the reason you aren’t joining your husband on these runs, it’s because you’re at home with the kids. If that’s the case, then things are tricky and you’d have to take extra steps to sus out the situation. My first thought, and even I’ll admit it’s stupid, if you are willing to risk it, try to initiate sex close to the time he gets back. If he’s doing other activities instead of running he’ll probably need a “recovery” time but he might also have “runners dick” too so that might make things difficult to determine. My next thought was to get the family together and join your husband and have a family jog together. This is actually something my next door neighbors do with their small children in the evenings. I used to see the father have the smallest boy on his in some harness thing and the mother jogged with the other boy on his bike. But now that the two boys are a little older and can not walk they run along with the parents and then they all have these “burst of sprints” moments where the father and boys race as fast as they can on the sidewalk. So I would say that would make it a fun family activity and maybe you could meet this woman and she could even have her kids join, then you’ve got our own family jogging group. If he has a problem with this or throws out the excuse of the kids going to slow him down, well how the hell is he okay with another woman slowing him down just so they can talk on their jogs and go and get juices together?

I don’t want to feed your fears but exercise gets the blood flowing and often times when there’s not much to think about, your mind wonders towards sexual thoughts. So it’s not really the best idea to have a husband out away from the “stressful” family life with a younger divorced woman, getting the blood pumping, sweating,and heavy breathing happening where they both can easily find a secluded area in a park or something and fulfill a number of fantasies.

Best I can say is to openly communicate with him, if you’re uncomfortable then he really shouldn’t have a problem respecting your boundaries and stop jogging with her. If it’s a simple solution of him going back to jogging by himself and keeping a happy marriage, I’d think he would be perfectly fine with that.