As the title says I(36m) get angry and jealous when my wife(35f) masterbates and I don't know why. I've never told her this at least not bluntly and I can't figure out why I feel this way.

We're currently in an odd place relationship wise yet I've always kind of had these feelings when she does. I don't give her grief for it because I know that I please her very well in bed both during foreplay and intercourse. She gives very obvious evidence when she is pleased so I know she's not faking it and I greatly enjoy pleasuring her in bed. Also because it's a natural thing to do and she shouldn't feel guilt for doing it. Plus it's not like she's reaching for a monster dido afterwards so it's not a male ego thing in that regard, she always favors her vibrator.

So why do I get upset and jealous when she does?

Edit 1: it's worth mentioning that she doesn't masterbate after rejecting me for sex. She has masterbated immediately after finishing sex but always asks me if it will hurt my feelings and I always say no and it doesn't bother me. She has masterbated before I got home but she says it's to get her warmed up for sex and that doesn't bother me either.