Erection goes down after holding in ejaculation

I don’t really have a problem with getting it up before sex but when I get close to that point of no return I hold it in. But Whenever I hold it in my erection goes down and I can get it back up with some effort however it’s such a buzz kill.
I feel like it’s starting to affect my partner as well because she might feel like I’m not attracted to her which is the complete opposite.
If anyone can give tips, it would be greatly appreciated!

I have had this before the biggest game changer is perspective. If you know she wants it but she hasn’t come yet then use that as your motivation. What I mean by that is, you edging yourself is also edging her but make it out as if you’re teasing her with it. Ask her “how bad she wants it” or pull out and rub your dick on her clit like slowly thrusting. If her squirming begging for you to fuck her doesn’t get you hard I’m not what will. Also LOTS of foreplay before. Hope that help!