Viagra? Secrets Kill

A few years into our relationship - with the odd break up in between - I moved into the bldg I live in now, in another apartment.
The sex had gone by the wayside, but happened occasionally.
There was an afternoon where the mood seemed to have hit Rob. I found it strange cuz just a few days back we were trying to have sex. Now I always had an orgasm or 2, ALWAYS. There were times when Rob didnt or couldnt get aroused throughout the entire act. I never understood that. The man you supposedly love, laying with you, enjoying both mine and his body and with Rob it just lay "limp".
My suspicions were always there. I would hear my friends talk about their sex lives and mine with Rob, paled in comparison. I always said to Rob that Im sure his parents had more sex that we did, and I was probably right.
At this point in my relationship, I snooped around, he had given me too many reason to snoop around.
I found Viagra in his bag once. I was blown away. Firslty I noticed a pill missing from the 4 pack he had. I didnt know he had bought those and I do know that he didnt pop the first pill and use it with me as we hadnt had sex for weeks at that point, and the time before that in which we did engage in sexual behaviour, Rob remained limp - no Viagra there.
I knew he had popped another one this day he wanted to have sex, but I declined. That I wasnt in the mood...I would have gone on if I knew he was popping Viagra to better the relationship. To keep our sexual lives going. I would almost appreciate or respect it a bit more, but he never told me and I asked him about it years later and at that point it no longer mattered.
Severe lies began at that point, not just with Viagra, but people he was talking to etc...more of the decline in motion...