I say all of the following with the caveat that I've never been married, so I can only speculate as to how I might deal with a similar situation if I were married. However, I have been involved with men with close female friends, and have generally taken the approach that until I have some concrete reason not to trust the situation then whatever issues I have with it are a product of my own insecurities and, therefore, more or less "my" problem to fix. Asking someone to pacify those insecurites by getting rid of the friend would likely prove to be only a temporary fix as the insecurities would just manifest themselves in some other way. And if there really is some larger trust issue, getting rid of the friend would again just mask the problem. In fact, I'm of the opinion that demanding someone disavow a relationship with a member of the opposite sex for no other reason than it just makes them feel threatened, is just the type of behavior that can ultimately lead to infidelity--maybe not in the shortrun, but over time.

Building and maintaining trust, it seems to me, isn't about eliminating all forms of temptation. For one, that's just unrealistic. For another, in my opinoin, infidelity is more often than not a byproduct of what happens within a marriage, not because of what happens outside of it. In that sense, the energy spent worrying about exes, coworkers, friends at the gym and riding buddies could be better spent nurturing and growing the relationship in more positive ways or, in some cases, working on yourself.

I'm not suggesting that Mel not listen to her husband's concerns or pay them any heed, but I would encourage both of them to identify what they're really about. Are they about his insecurities as a cyclist? Fear that she is looking elsewhere to have some of her needs met? Fear about her getting hurt on the road? Insecurities about his own attractiveness or manliness? Fear that they're growing apart? Assuming they're able to identify the real issue--which will admittedly require some honesty and introspection--then finding a solution that actually addresses it may obviate the need to "lose the riding buddy." Maybe he just needs reassurance that she finds him attractive and sexy. Maybe they need to come to a better understanding about what a healthy, balanced marriage means to both of them and whether it can or should include outside interests and people. Maybe he needs to admit that some of his insecurities about their respective athleticism are his to work through with her encouragement. Maybe he just needs to get to know the riding buddy himself.

And if she does decide to "lose the riding buddy," there's nothing wrong with making that decision for the health of the marriage, as long as it's a decision made voluntarily and not because of threats, compulsion or ultimatums.