Firstly, I am not in a regular relationship, I just have sex partners.
I get aroused well and can sustain an erection well during foreplay, but I tend to lose it just before intercourse.
Putting on a condom does distract me, but I don’t think this is sufficient to cause this problem. I do worry about this problem, and I think it only makes it worse.
What can I do to cure this?
Well, you’re right that worry does make matters worse. Losing the erection while trying to put on a condom is very typical of erectile dysfunction (ED) associated with worry. This issue is common and it called ‘condom collapse syndrome’
I advise you see a sex therapist and another thing you might like to try is to get any willing lady to put the condom on for you. If you can encourage her to do this by saying how sexy it is and how arousing it is when she strokes you as she does it. The chances are that you’ll feel so stimulated things will go better.