Potential Cuck in the making

Hi All,

First time posting, so I apologize if this is in the wrong subreddit. I've been dating my girlfriend for 6ish years not and our sex life has gotten very stagnant. While in a lot of ways this can be a problem and I think is somewhat unusual given our ages M 27 and F 28, it turns me on incredibly. I'd be lying if I said I didn't have an addiction to jerking off. I'll usually do it 1-2 times a day, when hungover I'll do it 3-4 times a day (often to posts in this subreddit, so thank you for the material haha).

As mentioned, I will often gravitate towards cuckold content as I have a fetish for humiliation since I started jerking off and cuckold has been a growing interest of mine over the past 3 years. This is due largely in part to our sex life slowing to 1-2 times a week and now I'm lucky if we have sex 1 time a week. She will universally use her vibrator and sex will last about 10 minutes. I'm not small and by many standards would be considered large at 7 1/2 inches but still love the idea of S&M.

What I'm getting at with this post, is how do I slowly bring this conversation up? At the very least, to a point of fantasy between her and I. I believe it would be very helpful in our sex life and honestly be something that would allow her to continue without wanting sex (her drive has slowly faded over the years while mine has remained high). It's at a point where she doesn't even really like to be touched that much and I want to capture any sort of sexual relationship I can with her. Part of me thinks that if she was with someone else (stronger, bigger downstairs, oozing sexuality) then she would be more into me. This concept does still turn me on due to my sexual desires, but it also puts me in a tough spot because I want to have that dynamic with her knowingly not putting out, if that makes sense. For example, I'd love if she said no to PIV sex but had me go down on her and I jerked off into my hand or something. I do want to note that she is rather vanilla in the sense of kinks and dirty talk, so it will need to be at her pace which I'm fine with.

Some ideas I've had:

• suggesting getting a dildo and shopping online with her (maybe she picks out a black one without my coercion)
• I've brought up chastity in the past but this seems like a long shot given the intensity of this option i.e. 24/7 would be a lot and seems more like a stage 5 type of thing while we are at stage 1.
• Bringing up to her that I'd like to go down on her more and don't expect anything in return.

Thanks all who have any suggestions or want to add any hot notes, I know the tone of this is more serious but also love some dirty talk too!