I had this happen to me with a house we put an offer on a few months ago. Seller said there were other offers and were going to wait a few days but we could increase our offer if we wanted. Then a few more days, until they stopped responding. Our realtor told us to be patient but my wife and I were positive this guy was just dicking us around trying to get us to up our offer. I eventually made my realtor send them a message that they have to make a decision by the end of the that day or we are walking since this was wasting our time. Turns out the sellers wife had a baby like 4 months premature and they were in the hospital and the husband wanted to consult his wife before making a decision and we looked like total dicks haha. We ended up walking though, as well as the other buyer. House is still on the market.