You're not being unreasonable and you're probably feeling confused, rejected and hurt, to name a few emotions that would be natural in this situation. Two years into a relationship is not long and the passionate side should still be thriving. Research shows the initial intense 'lust phase' of a relationship, mostly fueled by our sexual bio-chemicals, isn't designed to last more than eighteen months before it cools off. But that doesn't mean that by two years your sex life should have fizzled to the point of dissatisfaction, as in your case. We never match the same kind of crazy obsessive sexual chemistry as when two people first discover each other in the beginning stages of a relationship, but a couple, with some investment, this should remain hot and excited for years together.
Research indicates that "great sex" revolves around feeling connected, rather than any one physical technique. In your current situation there is a definite lack of connection between you two, not just in your sex life, but in your communication. How can you change the pattern in your intimacy if you can't get through to each other about your feelings?
The way you are communicating about your dissatisfaction clearly isn't working because it hasn't brought about satisfactory change. In a healthy relationship partners want each other to be happy, so if it's clear that they aren't generally a genuine effort is made to work together to fix the issue so that both partners can get back to being happy together again.
Rather than focus on the dissatisfaction you are feeling yourself, try to explore with him what's triggering his dissatisfaction with your sex life.
What does he account for the shift from a great sexual relationship to now, the preference to act as a single man and self service himself? Ask him if he feels the distance and disconnection between you also, and if he'd like to work on reigniting the intimacy. If you can reconnect as a couple in your communication and time spent outside the bedroom, the distance won't feel so great and it will be much easier to initiate sex between you. Build up to this by spending more romantic time together.
If you create shared experiences together that feel good and enable you to feel closer, that will translate into the bedroom. If it doesn't, then you know there is a hiccup or obstacle to your intimacy as a couple that needs deeper investigation and analysis to unearth what is wrong and how you can then fix it. This may require more honesty, and guided by a counselor can be very successful. Do not be surprised at how issues that seemingly have nothing to do with your sex life project themselves into your sexual intimacy and manifest there. While many couples engage in masturbation together and separately, it's not healthy for it to replace shared mutual pleasure to the extent that one partner remains dissatisfied, even after communicating about it. It's not only reasonable how you feel, it's essential that you do something about changing it.
Good Day!
Just personal preference.