Confusing situation with a guy from work: why does he acts this way? Plz help

I met a guy at work 3 weeks ago, we go along well, talk a lot, have lunch etc together. We'll only work together for the next 4 months so no need for "don't shit where you eat" advices...
He is often flirty, he hints compliments etc...
Today he suggested we go having dinner in town together after work, which we did. He took me to a place he knew, it was nice, we stayed 2-3 hours or so, he payed but we agreed i'd pay him back after and he didn't reject it.
After that he wanted to go on a walk, he wanted to take me to a nearby beautiful park, but it was closed so we ended up walking around. He was walking very closed to me at some point, i could feel a slight tension, hard to describe, nothing happened and i was tired and felt like going back home so he took me to the underground (after having walked 45min or so), he had these soft eyes when he said bye, he looked hesitating, he looked deeply into my eyes, silently for a few seconds before saying bye.
After he sent me a text saying "thank you for this evening".

Does it look like he likes me? When guys send you a thank you text after hanging out with you, doesn't mean it was kind of a date?

I'm guessing you don't have much experience with guys.

Just tell him how much you really enjoyed the evening and would very much like to go out with him again. By saying that, he will understand you have interest.

Oh and here's a tip: if you really like the guy, never offer to pay him back, this screams "we are just friends this is NOT a date", but instead offer to make him a home cooked meal.

Guys don't go out of their way to "hang out" with a girl if there was no interest. This was dinner, not a quick hotdog from a vendor on the street at lunch time, so it was a date.