Every time a girl opens up and says or does something nice to me that shows that shes interested in me, i auto diss them ... its like an automatic reaction

Example:

A HB8.5 is @ the gym with her group.. she sends multiple IOI's my way. Later when they are chillen in the jacuzzi i befriend their group and she is trying to ignore me the entire time...told the group it was my bday in a few days yada yada. after noticing her friends all like me she starts opening up to me via body language and little hints I could tell she's becoming comfortable around my presence. not a word has been said to me from her yet..... I get up from the jacuzzi and she assumes I'm leaving to go home so she abruptly says something like "ohh you're leaving? happy birthday again!!" in the most excited voice... could tell 100% she was into me ... so she finally opens up to me after all that time. I reply by saying "thank you but I'm not leaving" as I head to the shower stall near the jacuzzi with a slight smirk on my face as if to say thank you but your dumb lol... her face changed from happy as fk to the look of rejection.

Another Example:

Today at the gym me and my friends were stretching with our backs on the floor. A girl (HB 7.5) that has sent me multiple IOI's including 2 smiles on previous days walks into the room while we are stretching and says something along the lines of "oohh which guy can I have??" Kind of a slutty thing to say but in essence she saw us all laying down looking up while doing a chest stretch and she joked that she got to choose between us 3. So after she says " which guy can I have" i responded quickly by saying "not me" with a slight smirk on my face again.... she was like "why?!" and I was like lol relax im joking and she walked away with a kind of amused confused look on her face... I later approached, got her name (kino'd with handshake) talked for 1-2 mins to her and her friends and went back to stretching... but it seemed like she was kinda rejected too

I don't get what my issue is. I get a ton of IOI's from girls in general but when one actually shows TOO Much interest in me right away or abruptly... i just completely fuck it up by negging them wayyyy to hard which kind of makes the girls hate me cause im telling them they cant have me...

I mean I might have a shot at still hooking these two girls up but imo I kind of made it harder cause I denied them when they finally opened up to me and expressed interest...

why do I do this and how can I stop it from happening again? It's like I got 2 free invitations to hook them up but I throw it away by being a dick when they express interest...

Why am i doing this? I don't think I'm doing the right thing... am I? Any help would be appreciated!!!!!!!

EDIT:

I'd like to add that after I did that to the HB 8.5 ... I knew I had in a sense rejected her so I tried to make it up to her the next time I saw her and be more nice and the first day after that first meeting she kind of ignored me or was looking right through me when I looked @ her.... I guess she was auto rejecting me since I rejected her... on the second day I got her name finally and on the 3rd day she was nice again and actually came up to me and complimented me on my hair.....

so far what I've gotten is I need to handle things better under pressure...

The thing about me though is that i can carry a conversation very well... it's just that when they overtly make it known that they want me ( at the beginning of our interaction ) that it kind of throws me off and I push them away by being a dick