I think even a venial sin would require “slight consent” if you can permit the expression. Any degree of culpability requires a certain degree of consent.
As previous posts of fellow members remind us, it’s really important to not overly agonize about it.
It should be a consolation to know that some of the Saints (including St. Theresa of Avila) had to struggle against such human tendencies, and we are each at our own individual level in this regard.
In general, I believe it could be said that most of us (if not all)
"get" these thoughts from time to time , it’s part of the concupiscence linked to the human condition. My personal opinion would be that it’s what we do with these thoughts once we
"get" them, which determines whether it will be a sin.
The Epistle of St. James 1:12-15, NAB ] says it nicely
Blessed is the man who perseveres in temptation, for when he has been proved he will receive the crown of life that he promised to those who love him.
No one experiencing temptation should say, “I am being tempted by God”; for God is not subject to temptation to evil, and he himself tempts no one.
Rather, each person is tempted when he is lured and enticed by his own desire.
Then desire conceives and brings forth sin, and when sin reaches maturity it gives birth to death.
God Bless