Bought her a Big Dildo

I fantasize about being a cuckold, I like to read stories about it and
watch videos about it. I recently bought my GF a thick 8 in dildo.
When I used it on her she came hard twice. My 5.5 in never does that
to her. I am also a chronic masturbator, I need to make my gf more dominant, and make fun of my cock, How do I do it? Should I sendher emails with fantasies or get blackmailed by a phonesex girl?

I had one ex GF leave me for a guy with an 8.5 in cock, and
another ex GF use to still relax over at her old BF house when we were
dating. She even mentioned how another of her exes had a huge cock,
and how usually tall good looking guys with big dicks were assholes. I
bet she cheated on me.

Encourge your GF to cuckold you and let us know how it goes

Use role play and fantasizing when you are using the dildo on her...tell her to pretend it's another guy doing her while you watch...if she's had past lovers with large dicks tell her to think about one of them. By playing those type of mind games your wish may become reality. When I first used a dildo on my wife I asked her to pretend it was an old boyfriend...i then learned his name and I would say "Is Pedro fucking you right, honey?" "Is he making you feel good, baby?" "Fuck him good, baby...drain all his cum out!" I would let her manipulate the dildo herself and would say things like "Show me how he used to fuck you baby...show Daddy how you like to fuck him!" She would get extremely hot during these sessions and would cum like a horse. She then said to me: "If you don't stop that you're going to put ideas in my head and you might be sorry!" I assured her I would not be sorry and I would love it if she did it for real. I told her how much it would turn me on to see her perform with a good well hung stud.

Eventually we started talking about her doing the real thing since some guys at work were hitting on her and she thought one of them was good looking...I gave her permission to date him and she eventually took me up on it. She would then come home and tell me the details of their date, and eventually I was able to completely fulfill my wildest fantasy when I got in on the act performing threesomes on her with the other guy. It all has to be done gradually, but if you play your cards right you will succeed. I believe every woman would cuck her husband if she's completely sure she has his total approval and she feels she is pleasing his erotic desires. Let us know if you make any progress, and good luck!