You and him already being date for 6 years, and he plans to engaged you next week. But turns out

He married with someone else today

No, it's not because he's cheating. He did that because his parents knew his plan with you, and his parents immediately forbade him to engage you.

That's why he ends up on the altar now. You invited by his parents to see him with another woman, as you hold your tears difficultly.

Your eyes meet him. He feels a deep grief too, seeing you hurt in front of him.