It's a pretty frequent fantasy of mine to be "loaned" to a friend or acquaintance for an evening. I get the feeling that a lot of submissive women have the same fantasy. I'm kind of uncomfortable with the idea of doing it in RL, though, and I will explain why in many extremely pretentious pseudo-scholarly words:

I don't know if a lot of dominant guys fantasize about getting to borrow the wife of another man, though -- I've never really heard one mention it, as opposed to the fantasy of loaning out one's own spouse. Which sounds bizarre at first --men fantasize about GIVING UP SEX? And these are DOMS? -- but it actually makes sense. Historically, powerful men in a lot of cultures have used giving as a way to show off power and force others to recognize their status. While giving someone an expensive or high-status gift (such as inviting people to a fancy restaurant or giving away fabulous gift bags at a party) seems like an act of generosity, it is actually an act of dominance. It is a way of putting someone in your debt, obligating them to repay you in some unspecified way.

So of course "giving away" or "loaning out" a woman is an ultimate maledom fantasy -- it allows the dom to dominate his submissive in an extremely intimate and humiliating way, as well as allowing him to pull a major coup by dominating a fellow dom. However, while the submissive presumably enjoys the experience, I doubt that the dom who received this "gift" is going to feel really good about it afterwards, even if he enjoys the sexual encounter.

Recently, D. made a big deal of "showing me off" to a male friend of ours, inviting him to watch me try on different clothes and bras. I enjoyed the mild humiliation, but I felt a little bit uncomfortable on the behalf of the friend, who seemed to enjoy the display but then feel insecure and competitive (for instance, bringing up his prestigious job and high salary several times, which isn't normal behavior for him) for the rest of the day. I don't think that D. intended to make his friend unhappy, but I do think that he wanted to enjoy the feeling of being the big man in the room. You doms can't help it -- you like dominating us, but you really like dominating each other.

I would talk to your friend and see how *he* feels about this, and whether he is okay with getting back into BDSM after losing his wife. I'm concerned that he could see this as a pity gesture, or as a suggestion that he can't get a woman on his own. If you have the kind of friendship where you can honestly talk about this kind of feelings, that would be a big help. If not, um, do whatever it is that men do when they have feelings. If all three of you are really on the same page, go for it!