You seem to be suffering from performance anxiety and premature ejaculation. This can be alleviated if you spend more time in foreplay together and allow excitation and confidence between yourself for longer period before intercourse, then the anxiety would die down and you would be helped. There are anti-anxiety medications like alprazolam available on prescription which can be used for a week and they are known to help .
Avoid watching a lot of porn and even excessive masturbation hampers the performance. You may use squeeze technique to train your self and it is helpful in cases of premature ejaculation.
I hope i have answered your query,
wishing you safe sexual practices,
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