He invited me to this house party? (Guy's perspective?)

Anonymous
Some background information...

There's a guy I work with. We met about a year and a half ago. I adore him as a friend. He's incredibly attractive, and we get on fairly well. However I'm not romantically interested in him, as he's 3.5 years younger than me, and incredibly non-committal, to the point that he's told everyone that he doesn't want a girlfriend.

He's always been quite flirtatious with me, giving me a lot of eye contact, invading my space, being touchy feely, very obviously checking me out, and regularly complimenting me, telling me I'm "pretty", etc. Every so often he'd invite me to come out clubbing with him and his friends, but I'd usually turn it down, as I often had plans already, and honestly am not really into clubbing...I'd also feel a little old around his friends.

In the last few months, a new girl came along at work, but has since moved on, to another department, as she is a new graduate. He gradually started giving me less attention, and I soon found out they were hanging out together outside of work. And even more recently, discovered they are casually sleeping together, but he apparently doesn't want anyone to know. He doesn't know that I am aware. She comes and visits him in our department at work every so often, as she still works in the same building. She's never been particularly friendly to me for some reason.

Anyway...that brings us up to now.

I hadn't seen him for two weeks due to him.being on annual leave.

Just this week, I started wearing a skirt for the first time, and he saw me at work on Wednesday. He commented "you look...different" with a smile/smirk on his face, I just laughed. I was a bit more matter of fact with him though, with the knowledge of his "recent casual encounters". He soon told me that my hair looked nice, he also touched my back at one stage, near my bra strap. He then asked me what I'm doing on the weekend, then told me that there will be a house party at his house on Saturday night, for a girl's birthday, someone I don't know...I don't know any of his friends. Then he said "you should come!"

Why would he invite me to that? I'm 3.5 years older, don't know any of his friends at all, I'm not quite at the same level of attractiveness as he is, and I'm not THAT exciting to be around. Plus, he's already got a girl who is into him, and he is clearly attracted to her in some way.

Do you think he's just invited me as a mate/friend?

I'm a little puzzled. We're both in our twenties.
He invited me to this house party? (Guy's perspective?)
2 Opinion