I can't imagine many males being able to 'perform' if their partner had a terrified look on their face. That would feel a little rape-like I'd imagine...

To everyone telling him what he needs to do: he can't fix this with words. His GF needs to see a therapist and work on herself.

your life sucks number 666...

Write her a letter. I personally do not believe anyone who tells me I am pretty, but written down it's so much easier to accept that it might be true for some reason. Plus it's a solid thing to get back out and look at when she does have an bad patch. Try and get her to go to therapy because its so worth it or if she doesn't want to talk about it there's a site called MoodGYM which is a great online therapy you do at your own pace. Also, forget about sex for now - get comfortable kissing and touching each other fully dressed without it having to lead to anything further, and the pressure will decrease for her to feel body confident and for you to feel like you're not terrorising her. Good luck op - you sound a catch if you're so good about her body issues!

Hold her and tell her you love her, no matter what. Show her. It doesn't need to involve sexy timez.

First of all if she feels that way you have to take it slow then extremely slowly like could take months but do things to her body to make her feel comfortable. massages(non sexually) over the course of several times then eventually cover more area and jerk it before u do so you don't get worked up She'll become more comfy with you touching her everywhere, she may not want u to touch here or there like she may move your hand or something (don't get offended/upset) don't try again immediately perhaps not even the same session. However eventually when she lets you touch more then u can massage her (more sensually) and then over time boobs between her life legs but most importantly if you want this to work the main points to remember is it could take months or weeks who knows. Always try to prevent yourself from getting worked up, otherwise you get handsy and she is more uncomfortable. During all of this she'll only lower her guard to u because of your relationship but naturally still feel uncomfortable about her own body so don't make her anymore than she already is that will only work against you and take longer and start more problems outside of the bedroom. If you can manage this show her that you want to make her feel good because it makes you happy, in turn she'll want to do the same. She's had her whole life to be programmed this way. It will not go away overnight. So ideally eventually your sucking her nips and eating her snatch if she will let you/you're not a puss then she'll want you more etc. That's the physical part of the homework but during which time you have to express semi-often that you (nonsexually) find something about her attractive like I like your hair or dress or you look really such and such today. Also mean it don't say I love bla bla when u don't. Find ways to make her comfortable, (in general not just for sex). She may be more willing to let you pleasure her than her pleasure you at first but at that point you could (cut her off) not mean just kinda "I don't think I want to do that if you're not willing to for me" kinda thing. Either way some people find themselves ugly no matter how attractive they are but as long as your honest and learn to genuinely compliment her she'll want to make you feel good, not in a manipulative way just you trust each other more and. find each other more attractive. Also talk to her openly when she's not upset and say I hope u know just because u feel that way about yourself doesn't mean I do and I hope you can realize that you are beautiful even if you don't see it now. plus if its a weight thing eat well together make food together only shop for a week worth of food (vegan perhaps) at least with ingredients working out/eating right together makes it like 10 times easier than doing it alone.

my partner is terribly insecure. I've found that if I lie him down and just gently stroke all the parts I find beautiful, and explain why, he feels more handsome for a while- and OP, don't stick to the obvious. if there is, for instance, a curve of her neck that is graceful, point that out too. it's more personal that way.

It's a challenging situation, OP. Maybe you could try something intimate, but not directly sexual, like giving her a massage, to help her learn to relax in a situation where you are seeing her body. As far as sex and attractiveness goes, ask her if she thinks you are generally honest with her or a liar. Because it may be very hard for her to believe that her body is attractive. But she doesn't need to be objectively convinced of that. She just needs to trust you enough to believe you when you say she is attractive to you. If she trusts you in other things, that may be a way to shift her thinking on this. Just a suggestion; you know her and your relationship better than we do. And in the end, would she prefer you were attracted to a look of terror on her face? Because that would be a bit screwed up if you were.

why don't u just tell her that

Well that's a boner.