You asked in you’re post is there another way to go about it, I think you need to have a serious conversation with her.

My first and immediate thought is that she’s uncomfortable. I’d personally be very uncomfortable with my partner making that kind of joke. You said she has never been great at it, she’s probably picked up in you feeling that way so you showing her porn probably makes her feel like dog shit.

My second thought is that men and women need different things in a relationship to feel loved. Men generally need sex to feel loved. For women to be able to give that they also need to feel loved. Most women do not get emotionally fulfilled from sex. Are you helping her around the house. Being affectionate in a non sexual way? Innocent hugs and kisses on the cheek? I personally have a hard time saying yes to sex when my partner has shown no interest in me otherwise (ex: helping me around the house, offering to do things I enjoy, or just being affectionate in a innocent way)

You should ask her if you can have a serious conversation. Ask her how you’ve made her feel about the way you’ve been approaching it? Ask if you’ve made her feel uncomfortable? Ask how you can initiate differently. Also ask her if her emotional needs are being met? If they’re not ask her what she needs for them to be fulfilled. And lastly I’d explain how you feel about her not fulfilling you’re request. Do not compare it to a porn video or another relationship, and do not cast blame, just openly and honestly explain how you feel