My mom has married an American for 3 years. My mom sent in all the documents to remove conditions. We are waiting for an interview date to be scheduled. What would happen if my mom divorced him due to the relationship problems? Could we still get approved?

Yes. IF you had an interview, you would have to explain and probably file a waiver.

Thing is, divorces are not lightening fast. Most take at least a few months......some drag on for years. You might get AOS approval before the divorce even gets submitted.

Is the removal of conditions considered the 2nd AOS? I think that's what they talk about

AOS is accomplished via the I-485 and results in the granting of permanent residency status.

Yeah! that's what I thought.....

Removal of conditions is not AOS, although I have seen many people refer to it as such. (Some erroneously refer to removing conditions that are placed upon PR status as an "adjustment", but in point of fact the alien's status at this stage of the process is one of permanent resident, and all adjustment from non-immigrant to immigrant has already occured, and the removal of conditions is simply an additional condition of that status). It is important to use proper terminology, as particular circumstances and consequences are altered dependent upon when certain situations occur.