A question about friends

Today I had dinner with one of my colleagues.Maybe I can could (can is ability, could is potential) say that he is my friend.But I think it is wrong about this thing. it would be wrong. Because I have a BF and he has a wife. (Even) Though we are just friends,I don't think I should do it.think I should not do it.My BF may ("can" would be more natural) never go out with a girl for dinner without me.Maybe it is unfair,I don't know. Should not I I not have a heterosexual friend ?

First notebook entry: Introducing myself

Hi, I am Mucun from Japan.
When I was a junior high and high school student, I had studied English for 6 years.
Then, I began to study Chinese, and I've forgotten English little by little.

Studying Chinese is as interesting as studying English, I study more Chinense, but I want to study more English.
Now I can speak Chinese, but I think I wil forget it as I've forgotten English.

So my purpose is to remember these 2 languages.

Please help me, I will help you, too.