Sexual intercourse

My boyfriend and I have been together on and off for about 3 years the first year and a half, we never really had intercourse. The other year and a half we’ve been having sex more but the issue is I feel as if it’s not enough, we have sex once every 2 weeks or so.Here’s why I say that; he’s been struggling with an issue of not being able to stay hard. I feel as if he’s not attracted to me or it’s something that I do that bothers him but he swears it’s not me. We went to see a specialist and they prescribed him some medication but he doesn’t take it. The only time he takes the medication is when I remind him . When we do have sex he would go soft inside me or when I’m giving him oral he’ll go soft in my mouth... I’ve never dealt with this before him and I’m feeling neglected. I try to spice it up but nothing works. I’ve gotten to the point where I feel as if I’m begging my boyfriend to have sex with me and it’s not a good feeling ... Any advice ?