I have been with my partner for over 7 years and sex has been great for the first 6 years. For about a year now my Partner and I have been having issues with having basic sex. Oral is fine and on the odd occasion doggie style works. But missionary is most if not all the time impossible. I just can not stay hard long enough to get in and stay in. I know that my issue is that unless I am stimulated I go limp. But also my partner also has a few issues, but these have been helped with tablets to help with the constant vaginal bleeding which is caused by PCOS. We have used various gels and stuff but still nothing helps. My partner is on the big size but nothing that stops me getting in while I am on top (missionary), but if I am not hard long enough then I do not get in. As far as I know I do not have a problem staying hard if stimulated by my partner of myself. But getting in is the main issue. One question that comes to mind is, do I actually have the issue and maybe blood pressure or blood flow is causing it ? My other question is, am I on the onset of losing the ability of maintaining an erection ? I have spoken to my doctor and he does not see that there is any major issue as I have said that I can stay hard if stimulated. Can anyone suggest what I can do ?