If your on a visa that doesnt have multiple entry or leaving will make it expire they will pull you out and have you talk to an imigration official. You can add a multiple entry and or cancel a visa so that when you return there is not an issue.
You have a DTV approved. People that come visa exempt and try to stay for more than 180 days in a year on a tourist visa are the problem. You are living here at that point and the thais want you to apply for a long term visa