Guy i'm dating not into me?

Hi guys,

Bit of a weird one, but here goes. I'm a gay guy seeing a boy for the last 5 weeks or so. We have slept together in the same bed every night except one, and see each other every day. We have dinner dates, trips to London, cinema dates etc. He will turn up unannounced to my flat at 3am to see me and let himself into my flat to cuddle. He will travel at midnight an hour walking to come to see me (he lives 2 miles away)

He always says maybe one day I'll have your surname etc. and talks about things as if I am in his life 6 months, 3 years, 10 years down the line. We have good chemistry and a nice connection. We basically get on really well. I really like him.

We are not exclusive, just dating. I've been introduced to his family and friends casually and we all get on well. He said he wants to come and visit my family. But yesterday made me sad. I oversaw a text he sent to another guy (which is fine, we're not exclusive). But in that text though, I saw he said "i'm seeing someone but not really into him". Now I know gay guys can be complicated, like to keep options open etc. but I was quite suprised by the text considering how he's always asking to see me every day etc. Maybe he doesnt want to hurt the guy he's casually texting? But I can't help but feel upset and confused by the comment, when he's just asked if I want to have a romantic weekend to Paris with him...

Help please!