Bam Margera's Heated Spat with Fiancée After MCL Tear, Feared Drug Relapse

Bam Margera got into a loud argument with his fiancée that was caught on camera, and while it looked and sounded like they were at each other's throats ... Bam says it actually stemmed out of love.

The former "Jackass" star was arguing with Dannii Marie last Thursday outside of a Nashville hotel -- not long after he'd injured himself in a skate stunt that left him with a torn MCL and ACL.

In the video, obtained by TMZ, you can see Bam and Dannii shouting at each other -- it's a heated conversation, for sure, but Bam tells us all is well in their relationship.

He says the argument started after he stepped outside for a smoke break ... we're told Dannii apparently thought he was trying to sneak away to use hard drugs, as he has in the past.

Fact is, a lot of online trolls have speculated Bam might relapse after his injury if he were prescribed pain meds. We're told Dannii found Bam outside in the alley, and confronted him about that very possibility thinking the worst, but he insists the only thing he lit up was a cig.

Long story short ... Bam says Dannii was simply expressing concern for him, and he absolutely appreciates his woman looking out for his best interests. He credits her with keeping him on the straight and narrow with his sobriety.

Bam says he took a urine test that day to reassure Dannii he was clean, and he tells us he remains substance-free even to this day -- marking 6 months of sobriety.

Bam's manager Mike Quinn tells TMZ... "Good news, Bam remains sober. The personal incident outside a hotel, involving Bam and his fiancée, Dannii, stemmed from Dannii's concern for Bam's wellbeing. This misunderstanding between the couple was resolved positively, as expected moments later. Bam continues to take his regular voluntary urine tests to confirm his sobriety."