Moustache offensive

I don't want to go home today.
Sometimes I ask myself why relationships are so hard. I'm afraid the answer is I am relatively nuts. I did something inexplicably silly.
Last night I was helping R at his office when I happened upon some Christmas cards from other businesses on his desk. One of them was a photograph card from a woman I neither like nor approve of. I am jealous and I realize it isn't healthy to feel this way. It's not good for the relationship and it's not good for me. It wasn't a card different from any other card you'd get from a business. Signed by the company and a group photo on the front.
It was a smallish photograph really. I lost all sense of reality, grabbed a pen and drew a tiny little moustache across her face.
Now I don't want to go home. He won't think it's funny or cute.
He won't be thinking it will be a good laugh in about a year.
No, it's not relationships that are hard, it is that I am hard to have a relationship with.
And now I don't want to see what blowback there will be from the moustache offensive.