First, I'm not going to be judgemental and infer that your interest in getting stuffed by a big cock--even in front of your partner--means that you don't have strong romantic feelings for him. Kinks and fetishes are just that. Who's to say that your partner isn't just as much into watching your belly button bulging out as you are about exeriencing it?
That said, I've been in a situation like you are thinking about, and it was his idea. I had no problem with it, but they eventually did afterwards. She liked it a lot, and while he got off on it, I don't think he was ready for the conflicting emotions which the whole experience unleashed.
Would I do it again? Sure. Although I'd want some sexual attraction to be going on from my end first. But the husband would need to truly be up for it as well. I don't think I could say to anyone "Hey buddy look, your wife is getting what she wants fram a man for the first time," or anything hurtful like that. It's just not my thing. On the other hand, I'm not a saint, and (as with the experience I had) would enjoy making the wife cum as hard as I could make her cum, while being watched. I do have a strong exhibitionist streak. But if she started howling about getting off on my big cock, I'd probably give it to her harder and faster. I just know me.
I don't crave to be some MILFs bull, as there are so many complications that go along with it, but I'm not at all turned off by the thought of doing it again.
Does that answer your question?