SiN

of course it's ok.

it's (in my mind at least..) ok for either partner to not come, regardless of gender.

regarding 'feeling like a failure' -
i've told my bf on several occasions when i've not orgasm'd during sex, that it has _nothing_ to do with either of our abilities or whatever. just sometimes doesn't happen, and i'd hate for him to feel like he did anything wrong..

...and so i believe it also wouldn't be fair for me to take it personally if he didn't orgasm.

now...regarding your situation etc...

if you feel like you're not going to be able to orgasm during intercourse (which is a perfectly normal occasional feeling)
then you can either get off another way, or just stop, do it some other time.

no big deal, really.

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