<human>: Can you give me the gist of the text in a nutshell?

My bf has always been sort of interested in messing with people's heads and recently he's started to flirt innocently with girls at work. He claims it's only for fun. He became good friends with a colleague but his flirting may have gone too far since she felt the need to clarify that she was in a committed relationship and she didn't want to lead him on and that their flirting was dangerous. At work everybody teases them about being lovers. He told me this being very open and I felt hurt and got a bit angry at his mind games. After discussing we agreed he would be more careful with my feelings and stop his flirting.

We can look at each other phones, he says it's useless but he has agreed to let me check because he's not good with social clues and had innapropriate behaviour in the past with another girl ( he didn't understand she was interested in him and they went out on sort of dates). I used to be more trusting, this and other things he did or said have mined my self confidence.

Tonight I saw this conversation they had at 00.40, two days ago:

him> I'm a bit jealous that you spend so much time with X :S

her>Really? ;P

her>then, would you want to be with X? :)

him >stupid question to get an obvious answer.

X is just an object or a pet, it had a strange name.

I mean I don't know if this looks bad or it's innocent. It made me uncomfortable, I never checked before. 
What do you think about it?
<bot>: Boyfriend used to flirt. Told him for me it's not ok. Maybe he's flirting again texting his colleague about being jealous and wanting to spend more time with her. Wrote this at night.