Eating my wife after sex

I (M36) have a fetish that I haven’t had the courage to tell my wife (F33) I’ve always wanted to go down on my wife after sex (After I’ve finished in her). We have pretty vanilla sex 80% of the time. The other 20% can be pretty wild, however, I think she would tell me it’s gross. When we first got together she was pretty wild and would let me do whatever I want but young kids and busy lives has changed that. It’s usually a let’s get this in while we have time. So my question is how do I bring this up to her without immediately getting shot down?