Now, I have some problems with the idea of unconditional love. First of all, I don't think love is ever truly unconditional; and second of all, no matter how much we laud it as a goal or ideal, I'm not at all convinced that unconditional love is actually a good thing. At least, not when it comes to human beings. To pick an obvious example, if I love someone who keeps hurting me and and taking advantage of me, pretty soon I'm not going to love them quite so much (and soon after that, I'm not going to love them at all). This is not a failing on my part; it's a good and sensible reaction to unacceptable behavior.
So, no: I don't think that unconditional love (for either the husband or the wife) is a necessary ingredient for a successful marriage.
But the other half of this equation isn't just misguided; it's nonsensical. Unconditional love may be a bad idea, but unconditional respect is essentially a contradiction in terms. Respect is, by its very nature, something that must be earned. If it isn't earned, it isn't respect. It might be courtesy, or perhaps deference, but it can't be respect.
So, you know, at best this advice is misleading. At worst, it's deliberately designed to set up a situation where no matter how egregious the husband's behavior might be, the wife isn't supposed (read: allowed) to call him out for it. I'd like to think that that's a flaw, but I suspect for a lot of people it's a feature.
Generalized relationship advice is always suspect, but this seems pretty horrible even by those standards.
 I am aware of the theological assertion that God's love is unconditional. However, unconditional love is a very different proposition for an all-knowing, all-powerful being. Such a being is, by definition, simply not vulnerable. There is nothing limited creatures could do to harm it - ever. I'm not entirely sure that an all-knowing being could even be disappointed in any meaningful way. So God, if He exists, can afford to love unconditionally; for Him, there's no real risk or cost in doing so.