Rather than comparing homosexual sex to divorce, it's probably more helpful to compare it to unmarried heterosexual sex. Even though the homosexual aspect compounds the sin, both are still sin and the church ought to stand against both.
There are some churches where, despite what they officially believe, this simply doesn't happen much. Is the church for sexual purity, diligently fighting temptations those in the church themselves are most likely to struggle with (in most churches, this means heterosexual sex/p0rnography), or is the church merely against the sins it sees in outsiders?
I agree Jack.
Some evangelical congregations (many? most?) have grown comfortable enough with unmarried heterosexual couples living together while sitting in the pew that the Church leadership and members will often use a “don't ask don't tell” policy and just look the other way. That is more analogous to the question of how the Church deals with unrepentant homosexual couples than divorcing for unbiblical reasons. In both cases the persons involved can repent, though the path forward can be different for the heterosexual couple because they can repent and marry. But in both cases they need to repent. As someone mentioned before we tend to grade homosexuality as worse sin because the vast majority of us are not tempted by it. I tend to think we should treat practicing, unrepentant homosexuals the same as we treat others who live in a state of open unrepentant sin.