There are lots of parasitic draws on the battery while your trailer is not being used. e.g. LP gas detectors, etc. It is not unusual for a battery to go dead after a few weeks.
2018 F250 Lariat 6.2 4X4 w 4.30s, 2018 Wildcat 29RLX
2012 BMW G650GS, Demco Premiere Slider
1969 John Deere 1020, 1940 Ford 9N, 1948 Ford 8N
Jonsered 535, Can of WD-40, Duct Tape
Red Green coffee mugs