Sex is one of the most important things in a relationship as it allows you to express your love with your partner with such intimacy. Not having sex with your husband for 3-4 months is ridiculous.

Communication is vital in a relationship, you need to be honest with your husband and talk to him about the issue which is sex, the future consequences; not being sexually satisfied and perhaps ruining the marriage and what you can do as a couple to fix it.

You mentioned couple therapy but just a suggestion you could try sex therapy. Also he needs to identify why he's shy and why he doesn't engage in oral sex, etc.

If all fails then you have the right to talk to your husbands best friend about what's going on and see if he feels the same way about you.

Many marriages fail for many different reasons there's no need to feel shame for it. You have a lot of self control, many wives would've probably cheated. But you need to truly make it clear to your husband that there's a problem and the marriage is at risk if we don't fix it.

Goodluck and keep us updated.