No, men do not do this on purpose, far from it. If it were up to us we'd all take a lot longer and be the man that women brag about. Or at least hold off until the woman has also climaxed.
PE (premature ejaculation) can happen for a lot of reasons. Anxiety (he's worried about it so he can't stop thinking about it and then it happens!), he's really into you (a compliment if you think about it! He thinks you're so hot he can't help himself!), a high testosterone level(men are always ready), and some say evolution plays a role (The men that spread their seeds the best had children, so therefor the fastest ones), etc.
In any event, if he is generally a sweet and nice guy then he is not trying to be selfish. He wants you to brag about him, and he certainly doesn't want to feel inadequate.
Some tips to try:
Using a condom often lessens the sensitivity for the man, which will result in a longer performance. You can try doubling up on the condoms, but only if you realize the risks associated with improper use of condoms (STDs, Pregnancy). That's not how condoms are meant to be used, but it is said to lessen the feeling for the man.
Increasing sexual activity can also help. If a man has not ejaculated in quite some time, when you are having sex it more than likely will not last for long. You may notice a man will last quite a bit longer the second time if you have intercourse multiple times in one session.
For a more advanced technique, men can try controlling their PC (pubococcygeus) muscle. The PC controls ejaculation, among other things. He can find this muscle when he is urinating, it's how he would stop peeing midstream.
Mixing (Oral) it up can also help a man last longer. Stopping intercourse for him to perform oral on you serves two purposes: It keeps your momentum going and sets his back.
Finally, men know that we have a horrible reputation. Putting him under pressure will probably only worsen his anxiety and will not help. Be understanding and work with him to make him last.
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