[NSFW] ---- gf has trouble staying hard during sexy time

I'm transmasc and my girlfriend is a trans woman.

For about 1.5-2 months now, she's had a lot of trouble staying hard and orgasming, even if she begins our session incredibly hard. I wanna say usually within 30 minutes is when she starts to get soft, and that's usually when we're trying to move to penetration, but of course that's difficult if the boner goes away.

We're like 99% certain it's due to her HRT and not a mental block or anything, especially since she's on a pretty good dose of spironolactone. We both also know this can be common for people on feminizing hormones.

For those of you who've faced this problem, what helped? What didn't help?

She messaged her doctor about ED medication, so that's where we are currently.

Also a disclaimer: I'm not dissatisfied with our sex/intimacy. In fact, I think our sex is frickin awesome. And we're both working on internalizing the notion that good sex can happen without an orgasm. I just know it's getting increasingly frustrating for her, which frustrates me too.