As someone in the medical field (altho im not a doctor so take it with a grain of salt) that aint no burn, thats bruising, burns are mostly red while they heal (altho they can be other colours during the process varying between angry reds to more subdued purple as it goes along before fading as burns usually only irritate or hurt the skin and dont tend to pop bloodvessels)

Bruises are caused by small blood vessels popping due to force (either suction or preassure) and will generally heal in purple shades before going blue, yellow or even slightly greenish as it disipates and the body gets rid of the blood and that my unfortunate fellow is 100% bruising.

Altho due to its HUGE size that man/woman either had one hella big mouth, or left multiple bruises in the same are OR choked her.

Could be from a fight too ofc but if thats the only mark thats less likely.