If forever means until one or both people die then it's possible.
Naturally it all comes down to choosing the "right mate" and having the couple "growing together" as opposed to "growing apart".
One also has to consider the various levels or depths of love as well. Ultimately the goal is to find someone who expresses love (the way) you need to "feel loved" and vice versa in order to be happy.
It's possible for a man to love a woman so much that he would sacrifice his life for her if they came under attack. However this same man may never remembers their anniversary, nor buys her flowers, or plans romantic outings. Does he lover her? Sure!
By contrast a woman may cook and prepare a man's favorite meals, help him organize events to impress his employers, be his sounding board, and defend him against any verbal attacks however she never initiates sex or rarely wants it. Does she love him? Yes!
The problem with "love" is each of us has our own litmus test or ideas of what love is supposed to "look like".
Perception becomes reality.
Once we get beyond the "infatuation phase" of a new relationship and each person reveals their "authentic selves" many folks start to feel their mate doesn't love them. It's about their wants & desires.
There are only two ways to experience joy and peace of mind in relationships: We either get what we want or we learn to be happy with what we have. Accept them as (is) or move on.
The choice is up to us!