Why auto-stalemate against computers when the next move is a mate???

I've more or less learned the draw/stalemate rules (still don't understand why they both count as a draw if everyone says modern chess counts them differently) but I just had a game against a computer where they had just a king left and I moved in with both my rooks. Straight up easy rook roll, right? Nah that's a stalemate apparently. I did the pin right and everything and then on what would be the last rook move for a win the auto-stalemate popped up...why?? I'm honestly at this point just looking for a straight up moron-ed down explanation of stalemate rules (not just "learn how to play lulz") because I've never ever ever ONCE stalemated with a human, but it seems to happen every single time when I'm about to win against a PC. 

-Sincerely, 
Chess Player who is sick of AI being wusses and not accepting defeat

If you mean this game against Martin-BOT : Chess Analysis Board and PGN Editor - Chess.com

... it isn't an auto-stalemate. It's just a normal stalemate.

The Black King has no move. Stalemate. You screwed up.

Show me what move Black can make.

Lmao I understand now but somehow everyone has to be a douche about explanations on here. You could've left it at "Black king isn't under attack but any move would put it in check so there's no option but a stalemate"

Instead you decide to just tell me I screwed up and double down like "Oh really? You think you're right?? Then prove it to me, you the learner prove to me the experienced one why I'm wrong"

Lmao like thanks for the explanation, but piss off ;P

I would've been more receptive too if you didn't add the second comment ;P 

It's chess, no one cares, don't be a douche <3

In order to improve at chess, you have to man up and face your mistakes squarely.

Snowflakes do not get better at chess.

But sure... sort it out your own way.

Pissing off now.

Google "stalemate"

OK, now YOU are being a douche.

I added the second comment IN REPLY to your second comment. You know that.

Then, in order to cover up your error, you deleted your second comment and accused me of being a douche.

Good job.

Then they can woman up. Or cat up. or whatever.

Yea that was part of the frustration with it lol chess.com's own result didn't say anything about an inability to move it just lists insufficient pieces, 50 move rule, repetition and agreement.

But thank you for not being a douche lol, "Google x" is at least better than "It's your fault" 

Cuz I realized my second comment about what chess.com says (which is also in this thread replying to another comment now) was irrelevant so I deleted it, then when it refreshed I saw both your comments together within 1 min of eachother, longer than I was typing that one comment. So I assumed it was a double reply. So in that case it was an honest mistake and you're assuming things to get annoyed at me about lol

Even in that case, what's your goal in replying so quickly in such a condescending way to someone who is obviously trying to learn?? 

Nice teaching