Goimir, as someone who has been on the receiving end of a lot of attention when she wasn't feeling sexual, I'm going to try giving my input. It is meant to be from her point of view, which doesn't mean I'm taking her side but merely trying to explain to you how I think she might feel.
KLP, feel free to correct me if your situation is completely different.
Anyway, at the time, I was feeling a lot of pressure when I really couldn't have sex, and as a result whenever I was getting snuggly I would feel pressure again. Constantly wondering if he wanted sex. Stressed out if he asked me for a clear answer because I didn't want to say "yes, we will have sex" only to then realise I couldn't for whatever reason and have him say I promised. I felt like it was similar to saying days in advance that I would definitely have sex at a specific time, regardless of whether I felt like it when the time arrived. Except the timeline was much shorter, in that I would have been talking about the next half hour.
Basically, if he had expectations it killed it for me. So I found it easier to tell him not to expect it at all, so that at least the pressure was off my shoulders.
When I started getting more affectionate, he would get upset or accuse me of teasing him or ask me if we were going to have sex. These kinds of things didn't work for me at all. I would suddenly completely stop wanting it and all the work had to be done and built up again. I would much rather have had the sex just happen, on my own initiative, without it being expected by either of us, because I felt confident and trusting enough at the specific time the sex happened.
For whatever reason, she feels better about her boyfriend right now, or that's how you seem to feel. Maybe she feels like there are less expectations with him. Maybe it's because you kissed her when she was sick and her mind just interpreted it as an attack subconsciously, even though it wasn't your intention at all. If that's the case, you need to rebuild trust.
I realise the lack of sex must be a pain for you. But the more you stress that, the more pressure she'll feel. If you can have other outlets it feels like me the priority here would be working on your relationship. You need to rebuild that complicity you most likely used to have, so that your advances don't feel intrusive and her rejections don't feel hurtful.
If your frustration has led you to talk about sex more and more, it might make her feel like you only care about the sex, and feel her less valued, and want you more. I think if you can find a way to let her understand that it's not the case, and that you care about her first and foremost, and you just wish things could go back to how they were, then she would feel better about the whole thing.
Basically, you might have to court her again from the start. Whatever caused that split between the two of you, it needs to be fixed. And until it's fixed, even if she reaches 100% ability to have sex again, she might not feel up to having it with you.
I think her seeing her boyfriend will help her personally, and might help the two of you. I know time with my boyfriend would make me much more relaxed and likely to have sex with my husband when I was going through a rough time too. It also shows her that you care about her as a person and you want her to be happy.
KLP, your husband feels left out, it seems to me. I think you could try and plan some dates. Have them be out if you want, this should relax as it's pretty unlikely they'll turn out sexual. Or rent a movie to watch together on the couch, or play cards or a board game. Or take a walk. Just spending time together would probably be best for the two of you, and you can be intimate that way without it being sexual.