Some people have insecurities, not feeling comfortable with their body or having unease about themselves in general. When you become sexually active in a relationship, with whoever it is, you hope for comfort and confidence. It makes the whole sexual experience pleasurable and it should not be stressful.
The way someone carries themselves says a lot to the person they are attracting. When it comes to insecurity nothing can change the insecure persons mind, telling them they look good or you love them, means nothing. But no one wants to deal with this issue.
In reality it is not your partner’s job to instill a sense of security about your appearance and self esteem. If you are with someone you should already feel good enough about yourself so that your partner can feel the same thing you feel in the bedroom, which is pleasure.
This insecurity/anxiety issue can become tiring to the other person and becomes repetitive, reassuring your partner that everything they are working with is special and something you actually want.
It is better to be happy with what you have, especially if it’s something you can’t change about yourself. Your unchangeable qualities are the ones you have to learn to live with.
A tip to handle this situation is to be supportive and honest, but not in the critical way where you further damage your partners insecurities to a greater extent. Just explain how it is clearly not appealing to have bedroom issues and understand that there is a time and place to talk about what is really bothering them. If anything there can be a good reason for the insecurities, just hear your partner out.