UTI's and Sex

Hi

I am a female, 57 years old.

There is one paticular man in my life that I see Occassionally. We are a bit more than friends and always end up having sexual relations when we do get to see each other.

The last 2 times I had sex with him, I got a UTI. I did not tell him, as I don't see him that often but care very much about him and maybe this has nothing to do with it but I know he has prostate problems and they are under control. Are the UTI's due to his prostrate and if so,What can I do to avoid getting them?