Being your first post, a little advice: Tell us a lot more details.
Right now, the information we have is "Something's broken, what is it?"
We need more information like:
What make/model is your trailer?
How long have you owned it?
When did the problem start?
It could be a number of things that you need to narrow down and isolate.
1. Is it the GFCI or the breaker tripping?
2. Do you push the button on the outlet in the bathroom or flip the switch in the panel?
3. What else is plugged into all the outlets (especially the bathroom or kitchen)? Anything like a hairdryer, griddle, etc.
4. Have you used a GFCI wall tester? This will likely tell you if it's on the circuit or the refrigerator side.
Depending on your trailer, try to get to the back of the outlet. It could very well be that there is a screw or something going through the wiring.
2017 Forest River Surveyor 247BHDS...
...Tugged by a 2016 F250 XLT FX4 SuperCrew, Shortbed 6.2L, 4wd, 3.73...
...Joined with a Husky Centerline TS 800-1200lbs WDH