I said that an adulterer is a deceiver. I did not mention what the motivation "was".
I did, though, and you were responding to what I said.
How is breaking 3 of the 10 Commandments, trivial or nonconsequential?
Love God with all your heart and love your neighbor as yourself: these are all of the Law and the Prophets. Implied: Don't get hung up on what the text says by, for example, counting how many Commandments are violated.
If someone cheats on his/her partner, that may or may not be a serious problem depending on the rules of their relationship and how seriously the partner takes it. It is in any case in a completely different category than, say, the CEO of a major bank hiring lobbyists to provide bribes to legislators to make sure the law enables the bank to siphon vast amounts of other people's money into its own coffers. Or a televangelist using his charisma to get poor people to donate money they desperately need, to him, who clearly doesn't. Or a company dumping its well-paid workforce to hire dirt-cheap labor in a third-world country with an oppressive government that stomps all over workers' rights.
It's not that sexual sins are not wrong (although in many cases, e.g. premarital sex by unmarried people, I do think things traditional Christianity calls wrong aren't wrong), it's just a matter of perspective. Even when they're wrong, they're not horribly wrong, compared to sins that people like you tend to ignore.
And that's my point here. Jesus saw it more or less the way I do. He brushed off adultery with a sophistry and a "neither do I accuse you," but drove the money changers from the temple with a whip. He was lax about enforcing the Sabbath, and when some i-dotter called him on it, responded that the Law was made for man, not vice-versa. He hung out with the despised -- the poor, prostitutes, even the loathed tax collectors -- and castigated the well-regarded for thinking they were better than these people. He had no respect at all for wealth or status, and only contempt for ostentatious holiness. And he obviously didn't make a big deal about sins arising from love, or from carnal desire, focusing his big guns on those arising from greed and desire for power.
If you want to be like Jesus, go and do likewise.