Some men to do want to use a condom during sex. It is true that sex with a condom will reduce the sensation for men, somewhat. It's not the end of the world. Unless both parties are monogamous and have been tested for STD's, it is best to use a barrier method, such as a condom. But given the option of 1) condom or 2) no sex, most men will choose the condom.
The inside of a vagina is wet, in contrast, the inside of a condom is relatively dry. The wetness is part of the sensation that men miss by using a condom. Put some water based "personal lubricant" inside of the condom. This will make the inside of the condom feel more like a vagina (wet).
However, it is lubricant, so the condom can more easily accidentally slip off. Or a sneaky guy may slip it off - you shouldn't date a man who would do this.
You can also put the condom on with your mouth and put it on his penis, this video shows three techniques. The video is age-restricted, so you will need to watch it on YouTube.
A woman's reproductive organ makes her twice as likely as a man to catch an STD. If I was a woman, I would insist a man use a condom, unless both of you were tested for STD's and are in a monogamous relationship.