When my girlfriend is on top, which is the only position we can do currently (because I have a broken leg). We have sex for 1 to 2 hours however I do not cum. We do not use condoms it’s just that the position isn’t particularly great for guys. All I can say is mess around with positions and find one that is best for you.
To do with condoms making you feel less if your girlfriend/wife/fiancee will let you do anal. Then it will most probably make it a lot easier for you to come, due to it’s a tighter experience. This means you will not have the problem with condoms because it is a lot tighter and it will stimulate your member a lot more. Plus you may not have to wear a condom during this experience.
I know to some people this is taboo and I believe just mentioning to your girlfriend/wife/fiancee it will may get shot down but it is just my opinion. To fix this problem that I to face time to time.
Or you can try different positions due to it will make a large difference on the angle and some positions can make the pussy feel tighter like get her to lie on her side and squeeze her legs together while you are behind her and this will increase the experience for you.
If you masturbate several times a day. Which is what I used to do then you will have conditioned your member, if you carry on you will make it worse. The best thing you can do as many others have mentioned is take a break. One of the problems with conditioning yourself for sex which I haven’t seen anyone mention, is that it may make girlfriend/wife/fiancee very insecure about sex, due to she may start to believe she isn’t good in bed because she cannot make you cum every time. This can mean that she will have less sex with you or may be nervous about having sex with you.