I don't think there is a "one size fits all" description of what love feels like. I think all kinds of love encompass genuine affection, caring, support and commitment but the amount or extent of each depends on the type of relationship involved. In some relationships we give much more than we receive; in other relationships it may be the other way around. And in some relationships the give and take is about equal. I think the feeling of being loved, then, depends on the context of the relationship.
It seems that many of us who come to therapy with unmet needs for love or with a general feeling of deprivation seek out the unconditional love we should have been given from our parents. My T and I have talked about this quite often because I noticed that people here sometimes describe being loved by their T's in a way that feels "much better" than what they get from anyone else, and I didn't understand how it could feel so much better, but if it felt that good I wanted it, too. I didn't get what I wanted, though, and I was angry and hurt for quite some time. But we talked about it extensively, and he explained to me that those of us who were abused by our parents "seek more of that dependent love and are understandably angry/hurt when it is not forthcoming. Adult love is about give and take with ideally equal pleasure in the giving and receiving. Child love is almost always about receiving. As most therapists don't expect to receive from their patients, therapist love feels more pure to patients because it only involves getting, being much more like the fantasy of parent-child love."
The result of receiving that kind of love from a T is that it feels much better, much more nurturing than what we get from other relationships. It feels like we're finally getting some of what we missed out on when we were young. The problem, though, is that we can't replicate it in our real-life relationships with other adults unless we continuously place ourselves in dependent roles by seeking relationships with adults who allow that kind of dependence. And when those adults aren't people who have our best interests in mind, we can easily get hurt. The other problem is that we become accustomed to getting and needing this love that feels so good coming from our T, and then it's extremely difficult to give it up because nobody else can ever meet that need in the same way in real life. It can become almost like a drug because it feels so good for a little while, but eventually it wears off and we need it again and again in order to feel good about the relationship and about ourselves.
I think it's important to think about and talk with our T about different kinds of love before coming to the conclusion that we don't know what any kind of love feels like. Many of us have likely missed out on the unconditional love we should have received as children, but that doesn't necessarily mean we have never been loved by anyone. In therapy I've learned to recognize the different kinds of love I've experienced in my life, and I know I experience a kind of therapeutic love from my T that is appropriate for the nature of our relationship. And part of the way he shows how much he cares is by regulating the level of intimacy so that I don't get "too much" or "too little" from him. He gives me enough for me to know that I am cared for and valued, and most of the time I feel cared for and valued as well, although I don't always "feel the love" because there are times when I want more than he can or is willing to give me. As much as I may want more from him, he is careful to never give me so much that it undermines my motivation or desire to seek out close relationships with other adults in real life. He wants me to feel safe, secure, and cared for in our relationship but he never wants the therapeutic love he gives me to feel "too good" because he's not doing his job if he tries to make up for what I missed out on as a child or if he leads me to believe that if I get "just enough" from him it will be all I need to heal.