Exactly. I'm not a Bible expert by any stretch of the imagination, but if I'm not mistaken Mark 12:25 is one of only a few (and possibly the only one) passages that deal with marriage after death. Jesus plainly states there is no marriage in heaven, because we will be as the angels are. Angels are not given in marriage. Furthermore, we are taught in Scripture that men and women are bound by marriage only as long as they live.
" Know ye not, brethren, (for I speak to them that know the law,) how that the law hath dominion over a man as long as he liveth? For the woman which hath an husband is bound by the law to her husband so long as he liveth; but if the husband be dead, she is loosed from the law of her husband. So then if, while her husband liveth, she be married to another man, she shall be called an adulteress: but if her husband be dead, she is free from that law; so that she is no adulteress, though she be married to another man." - Romans 7:1-3 (KJV)
That is why marriage vows include, "Til death do us part." Once one spouse dies, the marriage covenant has ended, and no one is bound to it. Therefore, when the other spouse dies, why would they be held to a covenant that was already fulfilled? Yes, I realize one spouse doesn't always pass before the other, but you see what I mean.
Honestly, it would be like getting to Heaven, only to be told we can't come in because we didn't keep all of God's laws laid out in the OT. What would we say? "But I was under grace! Under the new covenant! Not the old one!"
.....Exactly.
If I'm off-base, someone please feel free to correct me, but that's the way I see it, for whatever that's worth.