I wouldn't say relationship. Spirits actually are drained of energy when manifesting on our plane, and that is why spiritual magick requires much more energy than most, and why energy is a common offering to spirits.
Spirits like to keep solitary, but will mostly help if they bargain offerings with you for help. They don't really take any curiosity in mortal affairs and like to keep to their affairs. Although there are times when spirits will ask highly, and will nearly do much more than normally to obtain what they seek.
Otherwise, day-to-day conversation and hugging-like friendship is very unlikely. It's hard to know if they even possess emotions.
If you are talking about spirits such as those from grimoires like the Key of Solomon, I would say business partners would be a more adequate term for it. However, with such grimoires you have various methods of looking a it and purposes for using it.
A spirit you leave an offering to may request such, in grimoires one would normally befriend one of the lesser beings and that one would serve as a familiar of sorts. In doing this a relationship which is continued will be established, this may mean regular offerings, or perhaps after time the spirit may work freely for you.
The goetia specifically are the 'workers' of the universe who are controlled by their angeic counterparts who all have bosses (archangels) who then answer to the God-name- the structure works like a business, and I would argue it is sensible to treat it like a business.
It's definitely possible, but you'd have to meet on the astral and learn to be respectful. Spirits aren't necessarily human, and they may think much more differently than you do. A lot of spirits also don't speak English, so don't expect to communicate with them in that way either. Keep in mind that spirits lie, trickster spirits exist, and not all of them are in your best interests.
A lot of spirits also require something in return, such as offerings like you suggested. Though, some may require things that are more extreme, such as your firstborn son (I haven't encountered any spirit who has required this, but I know people who have). In such cases, you should obviously refuse.
Additionally, always use discernment and protective measures when dealing with spirits. They may pretend to be someone you trust, such as your patron gods (if you have any) or ancestors. Always be careful and stay safe.
Communication and meeting with a spirit is quite different. You can communicate with spirits from where you are, but if one wants to meet and "see" the spirit, they'd have to shift to the astral, either through meditation or an out of body experience.